Biology/ Biochem
What bacteria is more likely to evoke an immune response: gram negative or gram positive?
Gram negative. Gram-negative bacteria have lipopolysaccharides on their outer-membranes while the gram-positive cell wall contains lipoteichoic acid. The inflammatory response to lipopolysaccharides is much stronger than the response to lipoteichoic acid.
Describe a gram negative cell wall
Gram-negative cell walls are very thin and contain peptidoglycan (like gram-positive) but in very small amounts. The peptidoglycan cell walls of these bacteria are adjacent to the cell membrane and are separated from the membrane by the periplasmic space. In addition to the cell wall and cell membrane, gram-negative bacteria also have outer membranes containing phospholipids and lipopolysaccharide. A prokaryote with this type of wall will stain pink given a crystal violet stain and a counterstain called safranin due to the fact it has an outer membrane that can block the purple stain: "Can purple enter? Negative." *The lipopolysaccharides are the part of the gram-negative bacteria that triggers an immune response in human beings.
Describe the molecular clock model
It is the idea that the more genetically similar two species are, the more recently the two species separated from each other.
Describe mitosis
It is the process by which two IDENTICAL cells are made from a single cell. Mitosis occurs in somatic cells, cells not involved in sexual reproduction. PMAT.
Describe the axon hillock
It integrates incoming signals by adding together the inhibitory and stimulatory signals that the dendrites receive. This is where the action potential is generated.
Describe punctuated equilibrium
It involves long periods of no change followed by relatively quick speciation Punctuated equilibrium suggests that changes in some species occur in rapid bursts rather than evenly over time.
What is juxtacrine signaling?
It is a type of signallying that does nto typically involve diffusion, but incvles a cell directly stimulating receptors of an adjacent cell
Describe the basic concept of interphase
It is composed of G1, S, and G0 phases. During interphase, individual chromosomes are not visible with light microscopy because they are in their less condensed form known as chromatin. This is because the DNA must be available to RNA polymerase so that genes can be transcribed. Note: During mitosis it is preferable to condense the DNA into chromosomes to avoid losing any genetic material during cell division
Describe the bacterial flagella
It is composed of a filament, a basal body, and a hook: The filament is a hollow, helical structure composed of flagellin. The basal body is a complex structure that anchors the flagellum to the cytoplasmic membrane and is also the motor of the flagellum The hook connects the filament and the basal body so that as the body rotates, it exerts torque to the filament which thereby spins and propels the bacterium forward.
Where does the umbilical cord come from?
It is formed from the remnants of the yolk sac and the allantois.
Describe Maltose
It is made up of two glucose molecules linked by an alpha-1,4 glycosidic bond
Describe the large intestine
It is primarily involved in water absorption. It is divided into three major sections: the cecum, the colon, and the rectum.
Describe the constant region of an antibody
It is this region that cells such as natural killer cells, macrophages, monocytes, and eosinophils have receptors for, and that can initiate the complement cascade.
What is a key characteristic of a zygote?
It is unicellular
Describe differentiation in terms of embryonic development
It occurs primarily via selective transcription where only the genes needed for that particular cell type are transcribed. Selective transcription is often related to the concept of induction which is the ability of one group of cells to influence the fate of nearby cells.
Describe Hill's coefficient
It quantifies cooperativity in enzymes: *If Hill's coefficient >1, positively cooperative binding is occurring, such that after one ligand binds, the affinity of the enzyme for further ligand binding increases *If Hill's coefficient <1, negative cooperative binding is occurring such that after on e ligand binds, the affinity of the enzyme for further ligands decreases *If Hill's coefficient = 1, the enzyme does not exhibit cooperative binding
What is the role of the ductus venosus?
It shunts blood returning from the placenta via the umbilical vein directly into the inferior vena cava
What is the function of ACTH?
It stimulates the adrenal cortex to synthesize and release corticosteroid hormones, most importantly glucocorticoids that help the body to resist stressors.
Describe Ubiquination
It targets a protein for degradation by a proteasome
What happens after a secondary oocyte is fertilized?
It will become a zygote. The zygote will then move to the uterus for implantation. As it does so, it undergoes rapid mitotic cell division in a process called "cleavage". The first type of cleavage officially creates an embryo, ending one of the zygote's defining characteristics: unicellularity.
Describe lymph nodes
Lymph nodes are a major component of the lymphatic system. They provide a place for immune cells to communicate and mount an attack; B-cells can be activated here as well/
What happens in anaphase?
The centromeres split so that each chromatid has its own distinct centromere, thus allowing the sister chromatids to separate. The sister chromatids are pulled toward the opposite poles of the cell by shortening of the kinetochore fibers.
What is a zwitterion
a zwitterion is a species with both a positive and a negative charge. At teh zwitterion state, pH= pI.
Describe oligodendrocytes and Schwan cells
Oligodendrocytes are glia cells of the CNS that produce myelin around CNS axons. Schwann cells are glia cells of the PeripheralNS that produce myelin around the PNS axons.
Where does the digestion of carbohydrates begin? Where does it end?
The chemical digestion of carbohydrates initiated in the mouth, but it is completed in the small intestine. Salivary amylase (active in the mouth) and pancreatic amylase (active in the small intestine) have the same function.
Describe the cecum
The cecum (C-shaped) is simply an outpouching that accepts fluid exiting the small intestine through the ileocecal valve and is the site of attachment of the appendix.
Why is the cell membrane compared to a capacitor?
The cell membrane is often compared to a capacitor because opposite charges are maintained on either side of the membrane
What happens in metaphase?
The centriole pairs are now at opposite ends of the cell. The kinetochore fibers interact with fibers of the spindle apparatus to align the chromosomes at the metaphase plate (aka equatorial plate)
Describe metaphase II of meiosis
The centrioles reach the opposite poles and the chromosomes line up at the metaphase plate
Describe anaphase II of meiosis
The centromeres divide, separating the chromosomes into sister chromatids, which are pulled to opposite poles
Describe cleavage in terms of embryo development
There are two types of cleavage indeterminate and determinate *Indeterminate Cleavage results in cells that can still develop into complete organisms. In fact, monozygotic twins have identical genomes because they both originate from indeterminately cleaved cells of the same embryo. Determinate Cleavage results in cells with fates that are already determined. These cells are committed to differentiating into a certain type of cell
Describe gut associated lymphoid tissue
These are immune tissues found in close proximity to the digestive system, which is a site of potential invasion by pathogens. These include the tonsils and adenoids in the head, Peyer's patches in the small intestine, and lymphoid aggregates in the appendix.
What are pattern recognition receptors?
These are special receptors found on macrophages and dendritic cells that aid in the innate immune response. PRRs are able to recognize the category of invader (bacterium, fungus, or parasite). This allows for the production of appropriate cytokines to recruit the right type of immune cells; each immune cell has different weapons that can target particular group of pathogens.
What vascular structure creates the most resistance to blood flow?
arterioles
What are the negatively charged amino acids?
aspartic acid (D), glutamic acid (E)
Hemidesmosomes
attach epithelial cells to the basement membrane
Any monosaccharides with a hemiacetal ring is considered ____
a reducing sugar. This is because as these monosaccharides switch between anomeric configurations, the hemiacetal rings spend a short time in the open-chain aldehyde form. Just like other aldehydes, they can be oxidized to carboxylic acids; these oxidized aldoses are called aldonic acids. Because aldoses can be oxidized, they are considered reducing agents and thus reducing sugars. Note: aldoses can also be reduced to alditols
Where is the action potential generated?
the axon hillock
What are the three major types of T-cells
helper T-cells, suppressor T-cells, and killer (cytotoxic) T-cells
What are the positively charged amino acids?
histidine (H), arginine (R), lysine (K)
Gastrin
hormone secreted in the stomach that stimulates secretion of HCl and increases gastric motility
What are tropic hormones?
hormones that have other endocrine glands as their targets; they require an intermediary to act. For example, gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. LH then acts on the gonads to stimulate testosterones production in the male and estrogen production in the female. IN other words, GnRH and LH do not cause direct changes in the physiology of muscle, bone, and hair follicles; rather they stimulate the production of another hormone by another endocrine gland that acts on these target tissues. Note: tropic hormones usually originate in the brain and anterior pituitary gland, allowing for the coordination of multiple processes within the body.
What are apolipoproteins?
proteins that bind lipids to form lipoproteins
What are ribosomes made of?
rRNA and proteins
What method does vasodilation use to cool the body?
radiation
What is the shape of the Michaelis-Menten plot for cooperativity?
sigmoidal
What are the types of point mutations?
silent, missense, and nonsense
What are isoforms?
slightly different versions of the same protein
What are optical isomers?
stereoisomers
What are analogous structures?
structures that perform a similar function but are not similar in origin also analogs and analogues
Anomers
subtype of epimers that differ at the anomeric carbon
What are deoxy sugars?
sugars with a -H replacing an -OH group like in DNA
Which chromosomes determine biological sex?
the 23rd
What is endothelium?
the tissue which forms a single layer of cells lining various organs and cavities of the body, especially the blood vessels, heart, and lymphatic vessels. It is formed from the embryonic mesoderm.
What is euchromatin?
uncoiled, acetylated, active chromatin
Which strand is the same as the mRNA strand?
the coding strand. They are both complementary to the template strand
What is metastasis?
the distant spread of cancerous cells through the blood stream
Where are disaccharidases secreted?
the duodenum
What is the neural crest derived from?
the ectoderm
What contains the vocal cords?
the larynx
What does the thoracic duct drain into?
the left subclavian vein
Where are clotting factors made?
the liver
Where is albumin made?
the liver
Where does the citric acid cycle take place?
the mitochondrial matrix
Before the placenta is established, the embryo is supported by the _______
yolk sac, which is also the site of early blood cell development
From zygote to gastrula, what are the various stages of development?
zygote --> 2-,4-,8-, and 16-cell embryo (once the division occurs the cell has become differentiated) --> morula --> blastula --> gastrula -->
Deamidation results in...
the release of NH3
What is tautomerization?
the shift from a carbonyl (keto) tautomer to an alkene with an alcohol (enol) tautomer.
Which is the coding strand?
the strand closest to the RNA sequence
What are the effects of the sympathetic nervous system on the following: heart rate blood blood glucose concentration bronchi digestion and peristalsis the eyes epinephrine
* increases heart rate *redistributes blood to muscles of locomotion *increases blood glucose concentration (so muscles can use it) *relaxes the bronchi (to allow more air in for action) *decreases digestion and peristalsis *dilates the eye to maximize light intake *releases epinephrine into the bloodstream (this is adrenaline)
What is the secondary structure of protein?
*Alpha helices: these coil clockwise around a central axis. They are stabilized by intramolecular hydrogen bonds between a carbonyl oxygen atom and an amide hydrogen atom 4 residues away. The side chains of alpha-helices point away from the core *Beta sheets: These can be parallel or anti-parallel. They are held together by intramolecular hydrogen bonds between carbonyl oxygen atoms on one chain and amide hydrogen atoms in an adjacent chain. The side chains of beta-sheets point above and below the plane of the beta-pleated sheet
What two supplemental energy reserves exist in muscle?
*Creatinine phosphate is created by transferring a phosphate group from ATP to creatine during times of rest. This reaction can then be reversed during muscle use to quickly generate ATP from ADP. creatine + ATP ↔ creatine phosphate + ADP *Muscle also contains myoglobin, which binds oxygen with high affinity. As exercising muscle run out of oxygen, they use myoglobin reserves to keep aerobic metabolism going. At a certain point, these reserves fail and the body has to switch to anaerobic metabolism which produces lactic acid
The three bases listed below are DNA sequences. Which amino acid is encoded by each of these sequences, after transcription and translation: *GAT *ATT *CGC *CCA
*GAT: mRNA codon= AUC; Isoleucine *ATT: mRNA codon= AAU;Asparagine *CGC: mRNA codon= GCG; Alanine *CCA: mRNA codon= UGG; Tryptophan
What are the different muscle fiber types in skeletal muscle?
*Red fibers: aka slow-twitch fibers They have high myoglobin content (hence red) and primarily derive energy aerobically. Red fibers also contain many mitochondria to carry out oxidative phosphorylation. *White fibers: aka fast-twitch They contain less myoglobin than red fibers (hence the white)
What are the requirements for Hardy-Weinberg?
*The population is very large (no genetic drift) *There are no mutations that affect the gene pool *Mating between individuals in the population is random (no sexual selection) *There is no migration of individuals into or out of the population *The genes in the population are all equally successful at being reproduced -->These criteria all imply that the population is not undergoing evolution <-- Provided that all of these conditions are met, the population is said to be in Hardy-Weinberg equilibrium, and we can use the p+q=1 and p^2+2pq+q^2 = 1 equations
Mnemonic for remembering the parts of a sarcomere
*Z- Z is the end of the alphabet and the end of the sarcomere *M- middle of the myosin filaments *I - I is a thin letter (thin filaments only) *H - H is a thick letter (thick filaments only) *A --All of the thick filament, whether or not it is overlapping
Which amino acids are hydrophilic? Which are hydrophobic? Where are they found?
*all amino acids with charged side chains (H,R,K, and D, E) are hydrophilic as are the amides (N & Q) and Serine and Threonine (S &T) --She's Taking No Questions. These amino acids are thus typically found on the surface of proteins. *amino acids with long akyl side chains (A, I, L, V, and F) are all strongly hydrophobic and thus likely to be found in the interior of proteins *The remaining amino acids fall in the middle and classify as neither.
What is the primary method of transporting free fatty acids in the blood>
Free fatty acids remain in the blood, bonded to albumin and other carrier proteins. A much smaller amount will remain unbounded.
What is gene therapy?
Gene therapy is a method of curing genetic deficiencies by introducing a functional gene with a viral vector
What type of hormone is insulin?
a peptide hormone
What is a potential space?
A potential space is a one in which there are two different tissue layers that are adhered, where the potential for a space exists, but is empty not normally present in healthy individuals. The subdural space and the interpleural space are "potential spaces".
What is the peak of an action potential?
+35 mv
During protein processing, what is the eventual fate of each of the following components: carbon skeleton, amino group, and side chains?
*The carbon skeleton is transported to the liver for processing into glucose or ketone bodies. *The amino group will feed into the urea cycle for excretion, Side chains are processed depending on their composition . *Basic side chains will be processed like amino groups, while other functional groups will be treated like the carbon skeleton.
How does the respiratory tract protect itself from infection?
*The first line of defense is the nasal cavity, which has small hairs (vibrissae) that help to trap particulate matter and potentially infectious particles. The nasal cavity also contains an enzyme called lysozyme. Also found in tears and saliva, lysozyme is able to attack the peptidoglycan walls of gram-positive matter and larger invaders. Underlying cilia then propel the mucus up the respiratory tract to the oral cavity. where it can be expelled or swallowed; this mechanism is called the mucociliary escalator. *The lungs, especially the alveoli, also contain numerous immune cells, including macrophages. Macrophages can engulf and digest pathogens and signal to the rest of the immune system that there is an invader. *Mucosal surfaces also contain IgA antibodies that help to protect against pathogens that contact the mucous membranes. *Mast cells also populate the lungs. These cells have performed antibodies on their surfaces. When the right substance attaches to the antibody, the mast cell releases inflammatory chemicals into the surrounding area to promote an immune response. Unfortunately, the see antibodies are often reactive to substances such as pollen and molds so mast cells also provide inflammatory chemicals that mediate allergic reactions.
Describe sucrose
alpha-D-Glucose with beta-D-Fructose via 1,2 glycosidic link
What is the threshold potential?
-55mV to -40 mV
What is the RMP of a neuron? What maintains it ?
-70 mV -- The value is closer to the resting membrane potential of K+ because the cell's membrane is slightly more permeable to K+ The Na/K+ ATPase
anomeric carbon
-chiral carbonyl carbon in cyclic form -carbon is bonded to both the ring O and a hydroxyl group
What are the three possible fates of pyruvate?
-conversion to acetyl-CoA by PDH complex -conversion to lactate by lactate dehydrogenase -conversion to oxaloacetate by pyruvate carboxylase
Most peptide and amino acid derivative hormones have names that end in ____.
-in or -ine. For example. insulin, vasopressin, thyroxine, triiodothyronine, etc.
Most steroid hormones have names that end in ____.
-one, -ol, or -oid. For example, testosterone, aldosterone, and other mineralocorticoids, cortisol, and other glucocorticoids, etc.
What are the functions of telomeres?
1) Protects the chromosomes from degrading 2) Their high G-C content also create exceptionally strong strand attractions at the end of chromosomes to prevent unraveling
What are the three important stress-related functions of cortisol
1) cortisol elevates blood glucose levels 2) Cortisol, being similar in structure to aldosterone, works with aldosterone to reabsorb/retain Na 3) Cortisol negative feedback restrains excess CRH
What are the 4 points of the Cell Theory?
1. All living things are composed of cells 2. The cell is the basic fundamental unit of life 3. Cells arise only from preexisting cells 4. Cells carry genetic information in the form of DNA that gets passed from parent cell to daughter cell. *According to this, viruses are NOT living organisms.
Describe the three checkpoints for the citric acid cycle
1. Citrate Synthase: ATP and NADH function as allosteric inhibitors of citrate synthase, which makes sense because both are products (indirect and direct, respectively) of the enzyme. Citrate also allosterically inhibits citrate synthase directly, as does succinyl-CoA. 2. Isocitrate dehydrogenase: This enzyme that catalyzes the citric acid cycle is likely to be inhibited by energy products ATP and NADH. Conversely, ADP and NAD+ function as allosteric activators for the enzyme and enhance its affinity for substrates. 3. alpha-Ketoglutarate dehydrogenase complex: The reaction products of succinyl-CoA and NADH function as inhibitors of this enzyme complex. ATP is also inhibitory and slows the rate of the cycle when the cell has high levels of ATP. The complex is stimulated by ADP and calcium ions.
How does the nervous system, which is derived from the ectoderm, end up on the inside?
1. First, a rod of mesodermal cells known as the notochord forms along the axis of the organism like a primitive spine -- in fact, remnants of the notochord persist in the intervertebral discs. 2. The notochord induces a group of overlying ectodermal cells to slide inward to form neural folds, which surround a neural groove. 3. The neural folds grow towards each other until they fuse into a neural tube, which gives rise to the CNS. 4. At the tip of each neural fold are neural crest cells. These cells migrate outward to form the PNS (including sensory ganglia, autonomic ganglia, adrenal medulla, and Schwann cells) as well as specific cell types in other tissues. 5. Finally, ectodermal cells will migrate over the neural tube and crest to cover the rudimentary nervous system
What are the events of the menstrual cycle in order
1. Follicular Phase 2. Ovulation 3. Luteal Phase 4. Menstruation -- menstruation occurs during the lowest levels of FSH and LH secretion Fault Of Loving Men - Eve loved Adam and shared the apple and that's why we have periods
Describe the steps of glycogenolysis
1. Glycogen phosphorylase releases glucose 1-P from the periphery of the granule until it encounters the first branch point. 2. Debranching enzyme hydrolyzes the alpha-1,4 bond nearest the branch point. 3. Debranching enzyme transfers the oligoglucose unit to the end of another chain and then hydrolyzed the alpha 1,6 bond, releasing the single glucose from the former branch.
Describe the formation of glycogen
1. Glycogen synthase makes a linear alpha-1,4-linked polyglucose chain. 2. Branching enzyme hydrolyzes an alpha-1,4 bond. 3. Branching enzyme transfers the oligoglucose unit and attaches it with an alpha-1,6 bond to create a branch. 4. Glycogen synthase extends both branches.
What are the six products secreted by the stomach?
1. HCl - kills microbes , denatures proteins, and converts pepsinogen into pepsin 2. Pepsinogen - cleaved in the stomach to pepsin; an enzyme that partially digests proteins 3. Mucus - protects mucosa 4. Bicarbonate- protects mucosa 5. Water - dissolves and dilutes digested materials 6. Intrinsic factor - required for normal absorption for vitamin B12
What are the phases of bacterial growth? Describe them.
1. Lag Phase: in this phase the bacteria is adapting to its new environment. As the bacteria adapts, an exponential growth occurs known as 2. Exponential Phase: aka log phase; this is the phase of exponential growth, but as the colony grow, resources are reduced and growth stops and the bacteria enter into 3. Stationary phase: after the bacteria deplete the resources in their environment they go into 4. Death phase
What are the three ways to remove neurotransmitters from the synaptic cleft?
1. Neurotransmitters can be broken down by enzymatic reactions (ex. acetylcholinesterase clearing out acetylcholine). 2. Neurotransmitters can be brought back into the presynaptic neuron using reuptake carriers (ex. dopamine and norepinephrine use reuptake carriers) 3. Neurotransmitters may simply diffuse out of the synaptic cleft.
What are the four steps of one round of beta oxidation
1. Oxidation of the fatty acid to form a double bond 2. Hydration of the double bond to form a hydroxyl group. 3. Oxidation of the hydroxyl group to form a carbonyl (beta-ketoacid). 4. Splitting of the beta-ketoacid into a shorter acyl-Coa and acetyl-CoA The process then continues until the chain has been shortened to two carbons, creating a final acetyl-CoA
List in order the 5 enzymes utilized in the PDH complex and their functions
1. Pyruvate dehydrogenase: PDH oxidizes pyruvate, creating CO2 while the remaining two-carbon molecule binds covalently to thiamine pyrophosphate (vitamin B12, TPP); Mg2+ is required for this process. 2. Dihydrolipoyl transacetylase: Dihydrolipoyl transacetylase oxidizes the remaining two-carbon molecule using lipoic acid and transfers the resulting acetyl group to CoA, forming acetyl-CoA. This leaves lipoic acid in its reduced form. 3. Dihydrolipoyl dehydrogenase: Dihydrolipoyl dehydrogenase uses FAD to reoxidize lipoic acid to allow it to facilitate future acetyl-CoA formation. As lipoic acid is reoxidized, FAD is reduced to FADH2. THs FADH2 can later transfer electrons to NAD+, forming NADH that can feed into the electron transport chain. *Pyruvate dehydrogenase kinase: Pyruvate dehydrogenase kinase phosphorylates PDH when ATP or acetyl-CoA levels are high, turning it off. * Pyruvate dehydrogenase phosphatase: Pyruvate dehydrogenase phosphatase dephosphorylates PDH when ADP levels are high, turning it on..
What are the steps to specialization of a cell?
1. Specification/determination 2. Differentiation
What are the 4 rules for being an aromatic ring?
1. The compound is cyclic. 2. The compound is planar. 3. The compound is conjugated (has alternating single and multiple bonds, or lone pairs, creating at least one unhybridized p-orbital for each atom in the ring). 4. The compound had 4n+2 (where n is any integer) pi electrons. This is called Huckle's rule. Note: re-read page 177 to understand why aromatic molecules are stable and fairly unreactive. DNA uses aromatacy for that reason: stability is important for storing genetic information and avoiding spontaneous mutations
How many ATP molecules does the citric acid cycle make?
10 ATP per acetyl coa From: 1 FADH2 = 1.5 ATP 1 GTP = 1 ATP 3 NADH = 7.5 ATP
What is the average molecular weight of an amino acid?
110 Da
How much ATP is made from a single pyruvate?
12.5
Other than glycolysis, what are 13BPG and PEP useful for?
13BPG and PEP are high energy intermediates used to generate ATP by substrate level phosphorylation. This is the only ATP gained in anaerobic respiration.
What is the pKa of carboxyl group
2
What is standard temperature and pressure?
273 K and 1 atm
Describe 3-phosphoglycerate kinase
3-phosphoglycerate kinase transfers the high-energy phosphate from 1,3BPG to ADP, forming ATP and 3PG. This type of reaction, in which ADP is directly phosphorylated to ATP using a high-energy intermediate, is referred to as substrate-level phosphorylation. Note: In contrast to oxidative phosphorylation in mitochondria, substrate-level phosphorylations are not dependent on oxygen, and are the only means of ATP generation in an anaerobic tissue.
How much ATP does oxidative phosphorylation generate?
30-32 7 from glycolysis and 25 from 2 pyruvate produced from glycolysis
What are the prokaryotic ribosomes?
30S and 50S; they join to make the 70S complex
What is the ratio of free fatty acids to glycerol produced through lipid mobilization?
3: 1
What is the total number of fused rings present in a steroid?
4 three hexagons and one penragon
How many ATP are produced in glycolysis?
4 are formed, but 2 are used during glycolysis reactions, so net gain is 2.
What are the eukaryotic ribosomes?
40S and 60S; they join to make the 80S complex
What is average cardiac output
5 L/min
furanose
5 membered ring
In what direction is DNA synthesized?
5' to 3'
In what direction is DNA transcribed and replicated?
5' to 3'
What direction is DNA read?
5' to 3'
pyranose
6 membered ring
What is the pKa of amino group
9-10
Describe bacterial genetic transformation
A bacterial genetic recombination in which bacteria absorb foreign DNA from their surroundings and incorporate it into their genome
Describe DNA sequencing
A basic sequencing reaction contains the main players from replication, including template DNA, primers, an appropriate DNA polymerase, and all four dideoxyribonucleotide triphosphates. In addition, a modified base called a deoxyribonucleotide is added in lower concentrations. Dideoxyribonucleotides (ddATP, ddCTP, ddGTP, and ddTTP) contain a hydrogen at C-3' rather than a hydroxyl group; thus, once one of these modified bases has been incorporated, the polymerase can no longer add to the chain. Eventually, the sample will contain many fragments (as many as the number of nucleotides in the desired sequence), each one of which terminates with one of the modified bases. These fragments are then separated by size using gel electrophoresis. The last base for each fragment can be read, and because gel electrophoresis separates the strands by size, the bases can easily be read in order.
What is the ductus arteriosus?
A structure in embryo connecting the pulmonary trunk to the aorta. (PDA in adults "P" patent)
Lactone
A cyclic ester with a ketone on the anomerix carbon: it is the result of oxidized aldoses entering cyclic form
What is a vitamin?
A vitamin is an essential nutrient that cannot be adequately synthesized by the body and therefore must be consumed in the diet
saturated fatty acid
A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton. --they are saturated with H's so there are no double bonds
What is an insertion mutation in terms of chromosomes?
A chromosomal insertion mutation occurs when a segment of DNA is moved from one chromosome to another. Small insertion mutations (including those where the inserted DNA is not from another chromosome) are considered frameshift mutations
What is a ganglia/ganglion?
A collection of neuron bodies (stroma) of the same type in the PNS
hemiacetal
A functional group that contains a carbon atom bonded to one -OR group, one -OH group, an alkyl chain, and a hydrogen atom.
acetal
A functional group that contains a carbon atom bonded to two- OR groups, an alkyl chain, a hydrogen atom.
Describe a heterocyclic compound vs a homocyclic
A homocyclic compound only consists of one element, for example carbon. A heterocyclic compound has other elements present. Like a histidine ring
Leptin
A hormone produced by adipose (fat) cells that acts as a satiety factor in regulating appetite.
Ghrelin
A hunger-arousing hormone secreted by an empty stomach
What is the basement membrane ?
A layer of connective tissue that anchors epithelial tissue to underlying tissues
Ovum
A mature egg cell that is ready to become fertilized
Muscle unit
A motor neuron and all of the muscle fibers it innervates
What is a nonsense mutation?
A mutation where the codon now encodes for a premature stop codon(also known as a truncation mutation)
What is a prosthetic group?
A non-protein component that forms a permanent part of a functioning protein molecule
What is the purpose of a nuclear localization signal?
A nuclear localization signal permits proteins to enter the nucleus
Describe Telophase 1 of meiosis
A nuclear membrane forms around each new nucleus. At this point, each chromosome consists of two sister chromatids joined at the centromere. Thus the cells are now haploid (once homologous chromosomes separate, only "n" chromosomes are found in each daughter cell). The cell divides into two daughter cells by cytokinesis. Between cell divisions, there may be a short period, or interkinesis, during which the chromosomes partially uncoil.
Describe Telophase II of meiosis
A nuclear membrane is formed around each new nucleus. Cytokinesis follows and two daughter cells are formed. Thus we end meiosis with up to 4 haploid daughter cells ( we say "up to" because oogenesis can result in less).
What is a nucleosome?
A region of DNA wound around histone proteins
What causes a right shift of the oxyhemoglobin curve?
A right shift is a sign of lower affinity and increased oxygen delivery to muscle (unloading) Exercise is the right thing to do: *increased PaCO2 *Increased [H+] (decreased pH) *Increased temperature *Increased 2,3-bisphosphoclycerate (2,3-BPG), a side product of glycolysis in red blood cells ^signs of a working muscle
What is a simple twitch?
A simple twitch is the response of a single muscle fiber to a brief stimulus at or above threshold. It consists of a latent period, contraction period, and relaxation period. The latent period is the time between reaching threshold and the onset of contraction. It is during this time that the action potential spreads along the muscle and allows for calcium to be released from the sarcoplasmic reticulum. The muscle then contracts, and, assuming calcium is cleared from the sarcoplasm, then relaxes.
What's the difference between nerves and tracts?
A single nerve may carry multiple types of information, including sensory, motor, or both. Tracts contain only one type of information.
What are episomes?
A subset of plasmids cable of integrating into the genome of bacterium
Describe the concept of a test cross
A test cross is used to determine an unknown genotype. In a test cross, the organism with an unknown genotype is crossed with an organism known to be homozygous recessive. If all of the offspring are of the dominant phenotype, then the unknown genotype is likely to be homozygous dominant. If there is a 1:1 distribution f dominant to recessive phenotypes, then the unknown genotype is likely to be heterozygous. Because a test cross is used to determine the genotype of the parent based on the phenotypes of the offspring, test crosses are sometimes called back crosses.
Describe the allantois
A tube extending from the yolk sac into the connecting stalk. It is involved in early fluid exchange between the embryo and the yolk sac. The allantois is surrounded by the amnion, a thin, tough membrane filled with amniotic fluid. This fluid serves as a shock absorber during pregnancy. In addition to forming the placenta, the chorion also forms an outer membrane around the amnion, adding an additional level of protection.
What are the fat soluble vitamins?
A, D, E, K all others are water soluble
What type of hormone is ADH?
ADH is a peptide hormone produced by the hypothalamus and released by the posterior pituitary
Describe antidiuretic hormone
ADH is secreted from the hypothalamus in response to increased plasma osmolality (sensed by osmoreceptors) or low blood volume (sensed by baroreceptors). Its action is at the level of the collecting duct, where it increased the reabsorption of water from the filtrate in the nephron. THis results in greater retention of water which results in increased blood volume and higher blood pressure.
What activates PFK-1?
AMP, fructose 2,6-bisphosphate, and insulin
Describe ketolysis in the muscle, renal cortex, and brain n prolonged fast
Acetoacetate ( a type of ketone body) picked up from the blood is activated in the mitochondria by succinyl-CoA acetoacetyl-CoA transferase (commonly known as thiophorase), an enzyme present only in tissues outside the liver. During this reaction, 3-hydroxybutyrate is oxidized to acetoacetate. The liver lacks this enzyme so it cannot catabolize the ketone bodies it produces.
Describe atrial natriuretic peptide
ANO is released from the heart to help regulate salt ad water balance. When cells in the atria are stretched from excess blood volume, they release ANP. This hormone promotes excretion of sodium and therefore increases urine volume. This effect is functionally antagonistic to aldosterone because it lowers blood pressure and volume, and has no effect on blood osmolarity.
Explain why ATP is an inefficient molecule for long-term energy storage
ATP is an intermediate-energy storage molecule and is not energetically dense. The high-energy bonds in ATP and the presence of significant charge make it an inefficient molecule to pack into a small space. Long-term storage molecules are characterized by energy density and stable, nonrepulsive bonds, primarily seen in lipids.
What inhibits PFK-1?
ATP, citrate, and glucagon
Embryonic mouse cells divide every 10 hours at 37oC. How many cells would be produced from an egg after three days?
According to the item, embryonic mouse cells divide every 10 hours at 37oC. Under such circumstances, and starting with a single egg, x cells would be present after three days (or 24 x 3=72 hours). The number can be calculated by tracking the doubling time: 1 → 2 → 4 → 8 → 16 → 32 → 64 → 128 → 256. At the end of 70 hours (approximately 3 days), there would be 128 cells, assuming that each cell underwent division 10 hours after its previous division.
What are the major enzymes of fatty acid synthesis?
Acetyl-CoA carboxylase and fatty acid synthase. They are stimulated by insulin
Describe Acetyl-CoA carboxylase
Acetyl-CoA carboxylase is activated in the cytoplasm for incorporation into fatty acids by acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid biosynthesis. The enzyme is activated by insulin and citrate. Acetyl-CoA carboxylase requires biotin and ATP to function, and adds CO2 to acetyl-CoA to form malonyl-CoA. The CO2 added to form malonyl-CoA is never actually incorporated into the fatty acid because it is removed by fatty acid synthase during addition of the activated acetyl group to the fatty acid.
How does acetyl-CoA shift the metabolism of pyruvate?
Acetyl-CoA inhibits pyruvate dehydrogenase complex while activating pyruvate carboxylase. The net effect is to shift from burning pyruvate in the citric acid cycle to creating new glucose molecules for the rest of the body. The acetyl-CoA for this regulation comes predominantly from beta-oxidation, not glycolysis.
If Acetyl-CoA is made in the mitochondria, how does it get into the cytosol for fatty acid synthesis?
Acetyl-CoA is the product of the pyruvate dehydrogenase complex and is coupled with oxaloacetate to form citrate at the beginning of the citric acid cycle. Remember that isocitrate dehydrogenase is the rate-limiting enzyme of the citric acid cycle; as the cell becomes energetically satisfied, it slows the citric acid cycle, which causes citrate accumulation. Citrate can then diffuse across the mitochondrial membrane. In the cytosol, citrate lyase splits citrate back into acetyl-CoA and oxaloacetate. The oxaloacetate can then return to the mitochondrion to continue moving acetyl-CoA.
Describe relaxation of muscle contraction
Acetylcholine is degraded in the synapse by the enzyme acetylcholinesterase. This results in termination of the signal at the neuromuscular juncion and allows the sarcolemma to repolarize. AS the signal decays, calcium release ceases, and the SR takes up calcium from the sarcoplasm. The SR tightly controls intracellular calcium concentrations so that muscles are contracted only when necessary. ATP binds to the myosin heads, freeing them from actin. Once the myosin and actin disconnect, the sarcomere can return to its original width. Without calcium, the myosin-binding sites are covered by tropomyosin and contraction is prevented.
Where does the largest drop in blood pressure occur?
Across the arterioles; this is critical because the capillaries are thin-walled and unable to withstand the pressure of the arterial side of the vasculature.
Which filament is associated with troponin and tropomyosin?
Actin! It has a "T" in it! Together these three make up the thin filament
What are the steps in fatty acid synthesis?
Activation of the growing chain (a) and malonyl-CoA (b) by attaching to an Acyl Carrier Protein, bond formation between these activated molecules (c), reduction of a carbonyl to a hydroxyl group (d), dehydration (e), and reduction to a saturated fatty acid (f)
What is adaptive radiation?
Adaptive radiation involves the divergence of one species into multiple species over time, which can occur when subgroups of the original species are separated or isolated in different environments so that these subgroups evolve independently of one another. This could be a result of disruptive selection.
Describe the adrenal gland
Adrenal glands are located on top of the kidneys. Each adrenal gland consists of a cortex and a medulla. Each part of the gland is responsible for the secretion of different hormones: The adrenal cortex secretes corticosteroids. These are steroid hormones that can be divided into three functional classes: glucocorticoids, mineralcorticoids, and cortical sex hormones. The adrenal medulla is responsible for the production of the sympathetic hormones epineprhine and norepinephrine.
How does insulin affect adipose tissue?
After a meal, elevated insulin levels stimulate glucose uptake by adipose tissue. Insulin also triggers fatty acid release from VLDL and chylomicrons (which carry triacylglycerols absorbed from the gut). Lipoprotein lipase, an enzyme found in the capillary bed of adipose tissue, is also induced by insulin. The fatty acids that are released from lipoproteins are taken up by adipose tissue and re-esterified to triacylglycerols for storage. The glycerol phosphate required from triacylglycerol synthesis comes from glucose that is metabolized in adipocytes as an alternative product of glycolysis Insulin can also effectively suppress the release of fatty acids from adipose tissue. During the fasting state, decreased levels of insulin and increased epinephrine activate hormone-sensitive lipase in fat cells, allowing fatty acids to be released into circulation.
Describe the translation and progeny phase of the virus life cycle
After infection, translation must occur in order for the virus to reproduce. Most viruses must enter the nucleus in order to be transcribed into mRNA. The mRNA then goes into the cytoplasm where it is translated into protein. Genetic material from positive-sense RNA viruses stays in the cytoplasm where it is directly translated into proteins by the host's ribosomes. Negative-sense RNA viruses require synthesis of a complementary RNA strand via RNA replicase which can be then translated to form proteins. DNA formed through reverse transcription in retroviruses also travels to the nucelus where it can be integrated into the host genome. Note: the viral genome must be returned to its original form before packaging
Describe the luteal phase of the ovarian cycle
After ovulation, LH causes the ruptured follicle to for the corpus luteum, which secretes progesterone. Remember that estrogen helps regenerate the uterine lining, but progesterone maintains it for implantation. Progesterone levels begin to rise, while estrogen levels remains high. The high levels of progesterone cue negative feedback on GnRH, FSH, and LH preventing the ovulation of multiple eggs.
What happens after a secondary oocyte is penetrated by a sperm?
After penetration of the secondary oocyte, the cortical reaction (a release of Ca2+ ions) occurs. These calcium ions depolarize the membrane of the ovum which serves two purposes: 1. Depolarization prevents further fertilization of the ovum by multiple sperm cells 2. The increased Ca2+ concentration increases the metabolic rate of the newly formed diploid zygote. Note The new depolarized and impenetrable membrane is called the fertilization membrane
Describe blastulation
After several cell divisions, the embryo becomes a solid mass of cells know as a morula (comes from the latin word for mulberry). Once the morula is formed, it undergoes blastulation which forms the blastula: a hollow ball of cells with a fluid filled inner cavity known as a blastocoel. The mammalian blastula is known as the blastocyst and consists of two noteworthy cell groups: the trophoblast and the inner cell mass. A blastula is an embryo with a blasted out cavity.
What are the agranulocytes?
Agranulocytes include the lymphocytes, which are responsible for antibody production, immune system modulation, and targeted killing of infected cells. Monocytes, which are phagocytic cells in the bloodstream are also considered agranulocytes. They become macrophages in tissues; many tissues have resident populations of macrophages with specific names (such as microglia in the central nervous system, Langerhans cells in the skin, and osteoclasts in bone).
What happens at Complex I of the ETC?
Aka NADH-CoQ oxidoreductase The transfer of electrons from NADH to coenzyme Q (CoQ) is catalyzed in this first complex. The main players of this complex are an iron-sulfur cluster and a flavoprotein that oxidizes NADH. The flavoprotein has a coenzyme called flavin mononucleotide (FMN) covalently bonded to it. FMN is quite similar in structure to FAD, flavin adenine dinucleotide. The first step in the reaction involves NADH transferring its electrons over to FMN, thereby becoming oxidized to NAD+ as FMN is reduced to FMNH2. Next, the flavoprotein becomes reoxidized while the iron-sulfur subunit is reduced. Finally, the reduced iron-sulfur subunit donates the electrons it received from FMNH2 to coenzyme Q (also called ubiquinone). Coenzyme Q becomes CoQH2. This first complex is one of three sites where proton pumping occurs, as four protons are moved to the intermembrane space
What happens at Complex II of the ETC?
Aka Succinate-CoQ oxidoreductase Just like complex I, complex II transfers electrons to coenzyme Q. While complex I received electrons from NADH, complex II actually receives electrons from succinate. Remember that succinate is a citric acid cycle intermediate and that it is oxidized to fumarate upon interacting with FAD. FAD is covalently bonded to complex II, and once succinate is oxidized, it's converted to FADH2. After this, FADH2 gets reoxidized to FAD as it reduces an iron-sulfur protein. The final step reoxidizes the iron-sulfur protein as coenzyme Q is reduced. Because succinate dehydrogenase was responsible for oxidizing succinate to fumarate in the citric acid cycle, it makes sense that succinate dehydrogenase is also a part of complex II. It should be noted that no hydrogen pumping occurs here to contribute to the proton gradient.
What happens at birth?
Aka parturition, it is accomplished by rhythmic contractions of the uterine stomach muscle, coordinated by prostaglandins and the peptide hormone oxytocin. There are 3 basic phases: 1. The cervix thins out and the amniotic sac ruptures (water breaking) 2.Strong uterine contractions result in the birth of the fetus 3. The placenta and umbilical cord are expelled (afterbirth)
Describe the adaptive immune system
Aka specific immunity. This system features B-cells and T-cells --anything else is part of the nonspecific immune system.
Describe prolonged fasting
Aka starvation LEvels of glucagon and epinephrine are markedly elevated during starvation. Increased levels of glucagon relative to insulin result in rapid degradation of glycogen stores in the liver. As liver glycogen stores are depleted, gluconeogenic activity continues and plays an important role in maintaining blood glucose levels during prolonged fasting; after about 24 hours, gluconeogenesis is the predominant source of glucose for the body. Lipolysis is rapid, resulting in excess acetyl-CoA that is used in the synthesis of ketone bodies. Once levels of fatty acids and ketones are high enough in the blood, muscle tissue will utilize fatty acids as its major fuel source and the brain will adapt to using ketones for energy. After several weeks of fasting, the brain derives approximately 2/3 of its energy from ketones and 1/3 from glucose. The shift from glucose to ketones as the major fuel reduces the quantity of amino acids that must be degraded to support gluconeogenesis, which spares proteins that are vital for other functions. Cells that have few, if any, mitochondria continue to be dependent on glucose.
Describe the postprandial state
Aka the absorptive or well-fed state This state occurs shortly after eating. The state is marked by greater anabolism (synthesis of biomolecules) and fuel storage than catabolism (the breakdown of biomolecules for energy). Nutrients flood in from the gut and make their way via the hepatic portal vein to the liver where they can be stored or distributed to other tissues of the body. The postprandial state generally lasts three to five hours after eating a meal.
Draw Alanine
Ala; A
What is the major glucogenic amino acid?
Alanine
How does alanine enter gluconeogenesis?
Alanine is converted to pyruvate by alanine aminotransferase
Hoe are alkyl halides named?
Alkyl halides are indicated by a prefix such as: fluro-, chloro-, bromo-, or iodo
What is the difference between D- sugars and L-sugars?
All D- sugars have the hydroxide of their highest-numbered chiral center on the right, and all L-sugars have that hydroxide on the left.
Describe the chiral amino acids in eukaryotes
All chiral amino acids in eukaryotes are L-amino acids in the Cahn-Ingold-Prelog system. This translates into an (S) absolute configuration for almost all amino acids except cystein which, although an L-amino acid, has an (R) absolute configuration because the -CH2SH group has priority over the -COOH group.
Describe MHC-1 molecules
All nucleated cells in the body display MHC class I molecules. Any protein produced within a cell can be loaded onto MHC-1 and presented on the surface of the cell. This allows the immune system to monitor the health of these cells and to detect if the cells have been infected with a virus or another intracellular pathogen; only those cells that are infected would be expected to present an unfamiliar (nonself) protein on their surfaces. Therefore, the MHC-1 is often called the endogenous pathway because it binds antigens that come from inside the cell. Cells that have been invaded by intracellular pathogens can then be killed by a certain group of T-cells (cytotoxic T-lymphocytes) to prevent infection of other cells.
Describe bacteriophages
Also called phage, or bacterial virus, these refer to any of a group of viruses that specifically infect bacteria. In doing so, they DO NOT actually enter bacteria, they simply inject their genetic material into the bacterium.
Describe base excision repair (BER)
Alterations to bases can occur with cellular insults. For example, thermal energy can be absorbed by DNA and may lead to cytosine deamination. This is the loss of an amino group from cytosine and results in the conversion of cytosine to uracil. Uracil should NOT found in a DNA molecule and is thus easily detected as an error; however, detection systems exist for small, non-helix-distorting mutations in other bases as well. These are repaired by base excision repair: First, the affected base is recognized and removed by a glycosylase enzyme, leaving behind an apurinic/apyrimidinic (AP) site, also called an abasic site. The AP site is recognized by an AP endonuclease that removes the damaged sequence from the DNA. DNA polymerase and DNA ligase can then fill in the gap and seal the strand.
What is alternative splicing and what does it accomplish?
Alternative splicing is the ability of some genes to use various combinations of exons to create multiple proteins from one hnRNA transcript. This increases protein diversity and allows a species to maximize the number of proteins it can create from a limited number of genes.
Describe how ketones can lead to acetyl-CoA formation
Although acetyl-CoA is typically used to produce ketones when the pyruvate dehydrogenase complex is inhibited, the reverse reaction can occur as well
Describe LDL
Although both LDL and HDL are primarily cholesterol particles, the majority of the cholesterol measured in blood is associated with LDL. The normal role of LDL is to deliver cholesterol to tissues for biosynthesis. However, cholesterol also plays an important role in cell membranes. In addition, bile acids and salts are made from cholesterol in the liver, and many other tissues require cholesterol for steroid hormone synthesis (steroidogenesis)
How do flatty acids get freed from adipose tissue?
Although human adipose tissue does not respond directly to glucagon, a fall in insulin levels activates a hormone-sensitive lipase (HSL) that hydrolyzes triacylglycerols, yielding fatty acids and glycerol -- epinephrine and cortisol can also activate HSL. Released glycerol from fat may be transported to the liver for glycolysis of gluconeogenesis. Note: HSL is effective with adipose cells but lipoprotein lipase (LPL) is necessary for the metabolism of chylomicrons and very-low-density lipoproteins (VLDL). LPL is an enzyme that can release free fatty acids from triacylglycerol in these lipoproteins.
Why is the citric acid cycle aerobic?
Although oxygen is not directly required in the cycle, the pathway will not occur anaerobically because NADH and FADH2 will accumulate if oxygen is not available for the ETC and will inhibit the cycle.
A concern in patients undergoing dialysis treatment is buildup of aluminum in the blood because of reduced blood pH. Aluminum most likely exerts its detrimental effects on the body by replacing other metal ions in enzyme cofactors and substrates. Why is that?
Aluminum exists in the environment as Al(OH)3 and is very poorly soluble under general conditions. However, under acidic conditions, Al(OH)3 dissociates to form Al3+ and water. The aluminum ion acts to replace iron (Fe3+) ions in some groups, as well as partially replacing some divalent cations (calcium, iron, magnesium). This negatively impacts protein function since a cofactor has been altered or the binding of the substrate is not correct.
Describe amino acid-derivative hormones
Amino acid-derivative hormones are less common than peptide and steroid hormones, but include some of the most important hormones including epinephrine, norepinephrine, triiodothyronine, and thyroxine. These hormones are derived from one or two amino acids, usually with a few additional modifications--for example thyroid hormones are made from tyrosine modified by the addition of several iodine atoms.
Describe amino acids in terms of acid base chemistry
Amino acids are known as amphoteric due to the fact that they have an acidic carboxylic acid group and a basic amino group, thus they can either accept or donate a proton depending on the pH of their environment.
Describe amino acids
Amino acids in a basic state contain two functional groups: an amino group and a carboxylic acid group. Some may have "R" sidechains. The sidechain "R" determines the properties of amino acids and therefore their functions. Note: most amino acids are chiral except for glycine which has an H as its R-group, making it achiral.
Describe aminopeptidase
Aminopeptidase is a peptidase secreted by glands in the duodenum that removes the N-terminal amino acid from a peptide.
What is lysozyme?
An antimicrobial . It is present in tears and saliva.
electrophile
An electron pair acceptor
nucleophile
An electron pair donor
creatine phosphate
An energy storage molecule used by muscle tissue. The phosphate from creatine phosphate can be removed and attached to an ADP to generate ATP quickly.
What is a synthase?
An enzyme that forms new covalent bonds without needing significant energy.
Describe galactose metabolism
An important source of galactose in the digest is the disaccharide lactose present in milk. Lactose is hydrolyzed to galactose and glucose by lactase, which is a brush border enzyme of the duodenum. Along with other monosaccharides, galactose reaches the liver through the hepatic portal vein. Once transported into tissues, galactose is phosphorylated by galactokinase, trapping it in the cell. The resulting galactose 1-phosphate is converted to glucose 1-phosphate by galactose-1-phosphate uridyltransferase and an epimerase. Note: epimerases are enzymes that catalyze the conversion of one sugar epimer to another (remember that epimers are diastereomers that differ at exactly one chiral carbon).
Plasmodesmata
An open channel in the cell wall of plants through which strands of cytosol connect from adjacent cells
What is the foramen ovale?
An opening between the right and left atria in the embryo and fetus.
Describe the structure of an antibody
Antibodies are Y-shaped molecules that are made up of two identical heavy chains and two identical light chains. Disulfide linkages and noncovalent interactions hold the heavy and light chains together. Each antibody has an antigen-binding region at the end of which is called the variable region (domain), at the tip of the Y. The remaining part of the antibody is called the constant region(domain).
Describe production of antibodies
Antibodies are produced by B-cells. Each B-cell makes only one type of antibody, but we have many B-cells so our immune system can recognize many antigens. Further, antibodies come in five different isotypes (IgM, IgD, IgG, IgE, and IgA). Different types can be sued at different times during the adaptive immune response, for different types of pathogens or indifferent locations in the body. Note: cells can change which isotype of antibody they produce when stimulated by specific cytokines in a process called isotype switching.
What causes the release of prolactin from the anterior pituitary
Anything that causes the hypothalamus to STOP producing prolactin-inhibiting factor (PIF) Note: PIF is actually dopamine
Describe apolipoproteins
Apolipoproteins, also referred to as apoproteins, form the protein component of the lipoproteins (VDL, HDL, etc.). Apolipoproteins are receptor molecules and are involved in signaling.
What are the 2 domains of prokaryotes?
Archaea and Bacteria
Describe Archaea
Archaea are single-celled organisms that are visually similar to bacteria but contain genes and several metabolic pathways that are more similar to eukaryotes than bacteria. They are often extremophiles, living in harsh environments (high temp, high salinity, no light) and often use chemical sources for energy (chemosynthesis) rather than light. Fun fact: Archaea also contain histones
How is the respiratory quotient expected to change when a person transitions from resting to brief exercise?
As a person begins to exercise, the proportion of energy derived from glucose increases. This transition to almost exclusively carbohydrate metabolism will cause the respiratory quotient to approach 1
Describe the action of the female hormones when menopause takes place
As a woman ages, her ovaries become less sensitive to FSH and LH resulting in ovarian atrophy. As estrogen and progesterone levels drop, the endometrium also atrophies and menstruation stops. Also, because the negative feedback on FSH and LH is removed, the blood levels of the two hormones rises -- this is menopause
How does helicase unwind DNA? What problem does that cause? How is the problem resolved?
As helicase unwinds DNA, it will cause positive supercoiling that strains the DNA helix. Supercoiling is a wrapping of DNA on itself as its helical structure is pushed ever further toward the telomeres during replication; picture an old-fashioned telephone that's become tangled on itself. To alleviate this torsional stress and reduce the risk of strand breakage, DNA topoisomerases introduce negative supercoils. They do so by working ahead of helicase, nicking one or both strands, allowing relaxation of the torsional pressure, and then resealing the cut strands.
What is the relationship between osmotic pressure and the direction of osmosis through a semipermeable membrane?
As osmotic pressure increases, more water will tend to flow into the compartment to decrease solute concentration. Osmotic pressure is often considered a sucking pressure because water will move toward the compartment with the highest osmotic pressure.
The accessory organs of digestion originate from which primary germ layer?
As outgrowths of the gut tube, the accessory organs of digestion arise from embryonic endoderm
Describe centomeres
As their names suggest, centromeres are a region of DNA found in the center of chromosomes. They are often referred to as sites of constriction because they form noticeable indentations. This part of the chromosome is composed of heterochromatin, which is in turn composed of tandem repeat sequences that also contain high GC-content. During cell division, the two sister chromatids can therefore remain connected at the centromere until microtubules separate the chromatids during anaphase
Draw Asparagine
Asn; N
Describe the menstruation phase of the ovarian cycle
Assuming that implantation does not occur, the corpus luteum loses its stimulation from LH, progesterone begins to decline, and the uterine lining is sloughed off (Since there is no longer progesterone to maintain it). The loss of high levels of estrogen and progesterone removes the block on GnRH so that the next cycle can begin
Which two types of glial cells, if not properly functioning, will make an individual most susceptible to a CNS infection?
Astrocytes nourish neurons and form the blood-brain barrier , which helps break down waste products and pathogens. Disruption of either of these mechanisms would increase susceptibility to a CNS infection.
What is the 5' cap?
At the 5' end of an hnRNA molecule, a 7-methylguanylate triphosphate cap is added. The cap is actually added during the process of transcription and is recognized by the ribosome as the binding site. It also protects the mRNA from degradation in the cytoplasm.
How do osmotic and hydrostatic pressures change at the capillary bed?
At the arteriole end of a capillary bed, hydrostatic pressure is much larger than oncotic pressure, and there is a et efflux of water from the circulation. As fluid moves out of the vessels, the hydrostatic pressure drops significantly, but the oncotic pressure stays about the same. Therefore, at the venule end of the capillary bed, hydrostatic pressure has dropped below oncotic pressure, and there is a net influx of water back into the circulation.
Where does oxygenation of a fetus occur?
At the placenta
What is the difference between autosomal cells and germ cells in terms of ploidy?
Autosomal cells are diploid (2n), having 2 copies of each chromosome. Germ cells are haploid , containing only one copy of each chromosome.
Describe the development of B-cells
B-cells are produced and mature in bone marrow. When B-cells leave the bone marrow they are considered mature but naïve because they have no yet been exposed to an antigen. The B-cells are then stored and later activated in the spleen. The activated B-cells turn into plasma cells to produce antibodies as part of adaptive immunity. Because these antibodies dissolve and act in the blood (rather than within cells), this division of adaptive immunity is called humoral immunity. B-cells= Bone marrow cells
How do antibodies become specific for a given antigen?
B-cells originally mature in the bone marrow and have some specificity at that point; however, antibodies that can respond to a given antigen undergo hypermutation or rapid mutation of their antigen-binding sites. Only the B-cells that have the highest affinity for the antigen survive and proliferate, increasing the specificity for the antigen over time.
If oligonucleotides such as mRNA were not degraded rapidly by intracellular agents, which of the following processes would be most affected? A. the production of tRNA in the nucleus B. the coordination of cell differentiation during development C. Decreased diffusion of gases during respiration D. the replication of DNA in the nucleus
B. the coordination of cell differentiation during development The destruction of mRNA prevents continuous protein production, allowing the cell to change its protein expression over time. B is the best answer because the coordination of cell differentiation during development is extremely sensitive to the timing of mRNA turnover. A and D are not the best answers because the exact timing of mRNA turnover is less critical to the successful completion of tRNA production (A) and DNA replication (D). C is incorrect because it is unlikely that an accumulation of mRNA would affect the diffusion of respiratory gases across the cell membrane. Thus, B is the best answer.
How do you calculate BMI?
BMI = mass/ height² *where mass in kg and height is in meters
Describe esterification of sugars
Because carbohydrates have hydroxyl groups, they are able to participate in reactions with carboxylic acids and carboxylic acid derivatives to form esters
Why are gluconeogenesis and fatty acid oxidation linked?
Because gluconeogenesis requires acetyl-CoA to occur (to inhibit pyruvate dehydrogenase and stimulate pyruvate carboxylase). The source of acetyl-CoA cannot be glycolysis because this would just burn the glucose that is being generated in gluconeogenesis.
Why is the genetic code considered degenerate? What is this caused by and what is the benefit?
Because more than one triplet codon can code for a specific amino acid; this is thanks to a wobble position in the codon. The degeneracy of the genetic code allows for mutations in DNA that do not result in altered protein structure or function. Note: Usually, a mutation within an intron will also not change the protein sequence because introns are cleaved out of the mRNA transcript prior to translation
Describe the action of proline in secondary protein structures
Because of its rigid cyclic structure, proline will introduce a kink in the peptide chain when it is found in the middle of the alpha-helix, thus it is rarely found in alpha-helices except in those that cross the cell membrane. It is also rarely found in the middle of beta-sheets. On the other hand, it is often found in the turns between the chains of a beta-sheet and it is often found as the residue at the start of an alpha-helix.
How do peptide hormones transmit their signal?
Because peptide hormones are charged and cannot pass through the plasma membrane, they must bind to an extracellular receptor. The peptide hormone is considered the first messenger; it binds to the receptor and triggers the transmission of a second signal, known as the second messenger. This relationship is known as the signaling cascade. Some common second messengers that use such cascade include cAMP, IP3, and calcium.
How do peptide hormones travel?
Because peptide hormones are generally water-soluble, peptide hormones can travel freely in the bloodstream and usually do not require carriers.
How do steroid hormones transmit their signal?
Because steroid hormones are derived from nonpolar molecules, they can easily cross the cell membrane. Hence their receptors are usually intracellular (in the cytosol) or intranuclear (in the nucleus). Upon binding to the receptor, steroid hormone-receptor complexes undergo conformational changes. The receptor can then bind directly to DNA, resulting in either increased or decreased transcription of particular genes, depending on the identity of the hormone (the receptor binds to DNA, the hormone itself does not). One common form of conformational change is dimerization, or pairing of two receptor-hormone complexes.
Why are lipid and carbohydrate synthesis referred to as nontemplate synthesis?
Because they do not rely directly on the coding of a nucleic acid, unlike protein and nucleic acid synthesis
Describe posttranslational processing
Before hnRNA can leave the nucleus and be translated to protein, it must undergo three specific processes to allow it to interact with the ribosome and survive the conditions of the cytoplasm: 1. intron/exon splicing 2. 5' cap 3. 3' poly-A tail Once all of these are done, hnRNA will be mRNA and is free to leave the nucleus
Describe beta oxidation
Beta-oxidation reverses the process of fatty acid synthesis by oxidizing and releasing (rather than reducing and linking) molecules of acetyl-CoA. The pathway is a repetition of four steps; each four step cycle releases one acetyl-CoA and reduces NAD+ and FAD (producing NADH and FADH2). The FADH2 and NADH are oxidized in the ETC, producing ATP. In the muscle and adipose tissue, this acetyl-CoA enters the citric acid cycle. In the liver, acetyl-CoA which cannot be converted to glucose, stimulates gluconeogenesis by activated pyruvate carboxylase.
Describe the process of ovulation
Between puberty and menopause, one egg per month is ovulated into the peritoneal sac which lines the abdominal cavity. It is then drawn into the falopian tube or oviduct which is lined with cilia to propel the egg forward.
Describe Bile
Bile is a complex fluid composed of bile salts, pigments, and cholesterol. Bile salts are derived from cholesterol. They are not enzymes and therefore do not directly perform chemical digestion. However, bile salts serve an important role in the mechanical digestion of fats and ultimately facilitate the chemical digestion of lipids. Bile salts have hydrophobic and hydrophilic regions, allowing them to serve as a bridge between aqueous and lipid environments. In fact, bile salts are much like the common soaps and detergents we use to wash our hands, clothes, and dishes. In the small intestine, bile salts emulsify fats and cholesterol into micelles. Without bile, fats would spontaneously separate out of the aqueous mixture in the duodenum and would not be accessible to pancreatic lipase, which is water-soluble. In addition, these micelles increase the surface area of the fats, increasing the rate at which lipase can act. Ultimately, proper fat digestion depends on both bile and lipase. Bile gets the fats into the solution and increases their surface area by placing them in micelles (mechanical digestion). Then lipase can come in to hydrolyze the ester bonds holding the lipids together (chemical digestion). Note: CCK also promotes the secretion of pancreatic juices into the duodenum.
How does bilirubin become a part of bile?
Bilirubin travels to the liver, where it i sconjugated (attached to a protein) and secreted into the bile for excretion
Describe the bones of the appendicular skeleton
Bones in the appendicular skeleton are typically long bones, which are characterized y cylinder shafts called diaphyses that swell at each end to form metaphyses, and that terminate in epiphyses. The outermost portions of bone are composed of compact bone, whereas the internal core is made up of spongy bone. Long bone diaphyses and metaphyses are full of bone marrow. The epiphyses, on the other hand, use their spongy cores for more effective dispersion of force and pressure at the joints. At the internal edge of the epiphysis is an epiphyseal (growth) plate, which is a cartilaginous structure and the sire of longitudinal bone growth. Finally, a fibrous sheath called the periosteum surrounds the long bone to protect it as well as serve as a site for muscle attachment. Some periosteal cells are capable of differentiating into bone-forming cells; a healthy periosteum is necessary for bone growth and repair.
What does mitochondrial DNA have in common with bacterial DNA?
Both mitochondrial DNA and bacterial DNA are a single circular chromosome of double stranded DNA that can self replicate during binary fission.
Describe branching enzyme
Branching enzyme is responsible for introducing alpha-1,6-linked branches into the granule as it grows. Branching enzyme: *Hydrolyzes one of the alpha-1,4 bonds to release a block of oligoglucose (a few glucose molecules bonded together in a chain, which is then moved and added in a slightly different location. *Forms an alpha-1,6 bond to create a branch.
Describe Brush border enzymes
Brush-border enzymes are present on the luminal surface of cells lining the duodenum and break down dimers and trimers of biomolecules into absorbable monomers.
Describe the process of oogenesis
By birth, all of the oogonia have already undergone DNA replication and are considered primary oocytes. These cells are 2n like primary spermatocytes and are usually arrested in prophase I. Once a woman reaches monarche, one primary oocyte per month will complete meiosis I, producing a secondary oocyte and a polar body. The division is characterized by unequal cytokinesis which distributes ample cytoplasm to one daughter cell (the secondary oocyte) and nearly none to the other (the polar body). The polar body generally does not divide any further and will never produce functional gametes. The secondary oocyte on the other hand remains arrested in metaphase II until further fertilization.
What receptors do CD4+ and CD8+ cells respond to ?
CD x MHC = 8 CD4+ cells respond to MHC-II (4*2=8) CD8+ cells respond to MHC-1 (8*1=8)
What does CETP do?
CETP promotes the transfer of cholesteryl esters from HDL to IDL, forming LDL.
Describe the initiation of muscle contraction
COntraction starts at teh neuromuscular junciton, where the nervous system communicates with muscles via motor (efferent neurons. This signal travels down the neuron until it reaches the nerve terminal (synaptic button), where acetylcholine si realesed into the synapse. In the case of the neuromuscular junction, the nerve terminal can also be called the motor end palte. Acetylcholine binds to receptors on the sercolemms, causing depolarization. Each nerve terminal controls a group of myocytes; together, the nerve terminal and it smyocytes constitute a motor unit. The depolarization triggers an action potential, which spreads down the sarcolemma to the T-tubules. The action potental travesl down the T-tubules into the muscle tissues to the sarcoplasmic reticulum. When the actioon potential reaches the sarcoplasmic reticulum, Ca2+ is ultimately releasdd. The calcium ions bind to a myosin, to which troponin is bound. This change exposes the myosin-binding sites on the actin thin filament
What is the equation for the bicarbonate buffer system in blood?
CO₂ (g) + H₂O (l) ↔H₂CO₃ (aq) ↔ H+(aq) + HCO₃-(aq)
What is the ACTH stress pathway?
CRH (hypothalamus) -> ACTH (pituitary) --> cortisol (adrenal glands)
Describe capillaries
Capillaries are vessels with a single endothelial cell layer and are so small that red blood cells must pass through the capillaries in a single-file line.
Describe the presence of carbohydrates on plasma membranes
Carbohydrates are generally attached to protein molecules on the extracellular surface of cells. Because carbohydrates are generally hydrophilic, interactions between glycoproteins and water can form a coat around the cell. In addition, carbohydrates can act as signaling and recognition molecules. For example, blood group (ABO) antigens on red blood cells are sphingolipids that differ only in their carbohydrate sequence. Our immune systems and some pathogens take advantage of these membrane carbohydrates and membrane proteins to target particular cells.
Describe cardiac muscle
Cardiac muscle is primarily uninucleated, but cells may contain two nuclei. Cardiac cells are connected by intercalated discs, which contain many gap junctions. These gap junctions are connections between the cytoplasm of adjacent cells, allowing for the flow of ions directly between cells. This allows for rapid and coordinated depolarization of muscle cells and efficient contraction of cardiac muscle. Cardiac muscles are able to define and maintain their own rhythm, termed myogenic activity (like in smooth muscle).
What is cardiac output? How is it calculated?
Cardiac output is the total blood volume pumped by a ventricle in a minute. Does it matter which ventricle one chooses? No, the two pumps are connected in series, so the volumes of blood passing through each side must be the same, much like the electrical current passing between two resistors in series must be the same. Cardiac output is the production of heart rate and stroke volume: CO=HR x SV
What are the proteins used for facilitated diffusion?
Carrier and channel proteins
What does glucose degradation refer to?
Cellular respiration
Describe the actions of the catecholamines
Catecholamines are secreted by the adrenal medulla and include epinephrine and norepinephrine, also known as adrenaline and noradrenaline. Catecholamines increase the activity of liver and muscle glycogen phosphorylase, thus promoting glycogenolysis. this increases glycogen output by the liver. Glycogenolysis also increases in skeletal muscle, but because muscle lacks glucose-6-phosphatase, glucose cannot be released by skeletal muscle into the bloodstream; instead it is metabolized by the muscle itself. Catecholamines act on adipose tissue to increase lipolysis by increasing the activity of hormone-sensitive lipase.
What is pinocytosis?
Cell drinking. Think of a "pino colada". Pinocytosis is the endocytosis of fluids and dissolved particles.
Describe Mismatch repair
Cells have machinery in the G2 phase of the cell cycle for mismatch repair these enzymes are encoded by genes MSH2 and MLH1, which detect and remove errors introduced in replication that were missed during the S phase of the cell cycle. These enzymes are homologous of MutS and MutL in prokaryotes, which serve a similar function.
What are inner cell mass cells?
Cells that protrude into the blastocoel and give rise to the organism to be born
What are trophoblast cells?
Cells that surround the blastocoel of a blastocyst and give rise to the chorion and later the placenta.
Describe cellulose
Cellulose is the main structural component of plants. A homopolysaccharide, cellulose is a chain of beta-D-glucose molecules linked by Beta-1,4 glycosidic bonds, with hydrogen bonds holding the actual polymer chains together for support. Humans are not able to digest cellulose because we lack the enzyme cellulase which is responsible for hydrolyzing cellulose to glucose monomers. Therefore, cellulose found in fruits and vegetables serve as a great source of fiber in our diet, drawing water into the gut.
What are centrioles?
Centrioles are found in an area of the cell known as the centrosome. They are structures as 9 triplets of microtubules with a hollow center. During mitosis, the centrioles migrate to opposite poles of the dividing cell and organize the mitotic spindle. The microtubules emanating from the centrioles attach to the chromosomes via complexes called kinetochores. Note: two centrioles make one centrosome
Describe ceramide and draw it
Ceramide is the simplest sphingolipid, it has a single hydrogen atom as its head group
Describe how amino acid catabolism can lead to acetyl-CoA formation
Certain amino acids can be used to form acetyl-CoA. These amino acids must lose their amino group via transamination; their carbon skeletons can then from ketone bodies. These amino groups are termed ketogenic for that reason. The formed ketone bodies are then converted into acetyl-CoA
Describe cholecystokinin
Cholecystokinin (CKK) is secreted in response to the entry of chyme (specifically amino acids and fat in the chyme) into the duodenum. This peptide hormone stimulates the release of both bile and pancreatic juices and also acts in the brain, where it promotes satiety.
Describe cholesterol
Cholesterol is a major component of the phospholipid bilayer and is responsible for mediating membrane fluidity. Cholesterol, like a phospholipid, is an amphipathic molecule containing both hydrophilic and hydrophobic components. Interactions with both the hydrophobic tails and hydrophilic heads of phospholipids allows cholesterol to maintain relatively constant fluidity in cell membranes: *At low temperatures, it keeps the cell membrane from solidifying *At high temperatures, it holds the membrane intact and prevents it from becoming too permeable. Cholesterol also serves as a precursor to many important molecules, including steroid hormones, bile acids, and vitamin D.
Describe chylomicrons
Chylomicrons are highly soluble in both lymphatic fluid and blood and function in the transport of dietary triacylglycerols, cholesterol, and cholesteryl esters from the intestine to tissues. Assembly of chylomicrons occurs in the intestinal lining and results in a nascent chylomicron that contains lipids and apolipoproteins.
Describe chymotrypsin
Chymotrypsin cleaves at the carboxyl end of phenylalanine, tryptophan, and tyrosine. It breaks apart the amine bond by adding a hydrogen atom to the amide nitrogen and an OH group to the carbonyl carbon in a process known as hydrolysis.
What are cilia and flagella in terms of eukaryotes
Cilia and flagella are extensions to a cell that provide motility (flagella). They also increase a cell's surface area (cilia). Cilia move in a back-and-forth motion while flagella move in an undulating motion. They are motile structures composed of microtubules, both have a 9+2 structure (this is seen ONLY in eukaryotic organelles of motility).
How do antibodies destroy pathogens?
Circulating antibodies can opsonize pathogens (mark them for destruction by phagocytes), cause agglutination (clumping) into insoluble complexes that are ingested by phagocytes, or neutralize pathogens by preventing it fro invading tissues
What are the three types of bacteria shapes? Draw them.
Cocci, bacilli, and spirilli
What is a cofactor/coenzyme?
Coenzymes are nonprotein organic or metalloorganic molecules that are crucial to the function of the enzyme. Many of these compounds are derivations of vitamins found in the organism's diet highlighting the importance of proper nutrition. --may also be an enzyme itself Cofactors are inorganic metal ions such as Mg2+, Mn2+, or Zn2+. Cofactors, like coenzymes, are crucial to the function of the enzyme. Both cofactors and coenzymes can be permanently bound to the enzyme and thus can be considered prosthetic groups Note: not all coenzymes or cofactors have permanent associations with enzymes but, rather, transient interactions with the enzyme.
What causes conjoined twins?
Conjoined twins come from monozygotic (identical twins) that did not fully separate.
Describe convergent evolution
Convergent evolution refers to the independent development of similar characteristics in two or more lineages not sharing a recent common ancestor. For example, fish and dolphins have come to resemble one another physically, though they belong to different classes of vertebrates. They evolved certain similar features in adapting to the conditions of aquatic life.
Draw Cysteine
Cys; C
Describe the malate-aspartate shuttle
Cytosolic oxaloacetate, which cannot pass through the inner mitochondrial membrane, is reduced to malate which can. This is accomplished by cytosolic malate dehydrogenase. Accompanying this reduction is the oxidation of cytosolic NADH to NAD+. Once malate crosses into the matrix, mitochondrial malate dehydrogenase reverses the reaction to form mitochondrial NADH. Now that NADH is in the matrix, it can pass along its electrons to the ETC via Complex I and generate 2.5 ATP per molecule of NADH. Recycling the malate requires oxidation to oxaloacetate, which can be transaminated to form aspartate. Aspartate crosses into the cytosol and can be reconverted to oxaloacetate to restart the cycle.
Describe cytotoxic T cells
Cytotoxic T cells (Tc or CTL, for cytotoxic lymphocytes), also called CD8+ T-cells, are capable of directly killing virally infected cells by injecting toxic chemicals that promote apoptosis into the infected cell. CD8+ T-cells respond to antigens presented on MHC-I molecules. Because MHC-I presents endogenous antigens, CD8+ T-cells are most effective against viral (and intracellular bacterial or fungal) infections.
Other than glycolysis, what is DHAP useful for?
DHAP is used in hepatic and adipose tissue for triacylglycerol synthesis. DHAP is formed from F16BP. It can be isomerized to G3P, which can then be converted to glycerol, the backbone of triacylglycerols. DHAP is an intermediate.
What is the function of DNA polymerases?
DNA polymerase are responsible for reading the DNA template, or parental strand, and synthesizing the new daughter strand. The DNA polymerase can read the template strand in a 3' to 5' direction while synthesizing the complementary strand in the 5' to 3' direction. This will result in a new double helix of DNA that has the required antiparallel orientation.
What eukaryotic polymerase(s) assemble the sliding clamp?
DNA polymerase delta and epsilon, assisted by the PCNA protein
What eukaryotic polymerase(s) replicated mitochondrial DNA?
DNA polymerase gamma
What is the relationship between amino acids and codons?
Each codon represents only one amino acid however, most amino acids are represented by multiple codons
What is the charge on DNA and RNA?
DNA and RNA have a sugar-phosphate backbone. Since phosphates carry a negative charge, DNA and RNA have an overall negative charge.
Describe DNA cloning
DNA cloning is a technique that can produce large amounts of desired sequence. Often, the DNA to be cloned is present in a small quantity and is part of a heterogenous mixture containing other DNA sequences. The goal is to produce a large quantity of homogenous DNA for other applications. Cloning requires that the investigator ligate the DNA of interest into a piece of nucleic acid referred to as a vector, forming a recombinant vector. Vectors are usually bacterial or viral plasmids that can be transferred to a host bacterium after insertion of the DNA of interest. The bacteria are then grown in colonies, and a colony containing the recombinant vector is isolated. This can be accomplished by ensuring that the recombinant vector also includes a gene for antibiotic resistance. The resulting colony can then be grown in large quantities.
What are DNA libraries and how are they produced?
DNA libraries are large collections of known DNA sequences; in sum, these sequences could equate to the genome of an organism. To make a DNA library, DNA fragments. often digested randomly, are cloned into vectors and can be utilized for further study. Libraries can consist of either genomic DNA or cDNA: Genomic libraries contain large fragments of DNA, and include both coding (exon- the exon is expressed) and noncoding (intron) regions of the genome. cDNA (complementary DNA) libraries are constructed by reverse-transcribing processed mRNA. As such, cDNA lacks noncoding regions, such as introns, and only includes the genes that are expressed in the tissue from which the mRNA was isolated. For that reason these libraries are sometimes called expression libraries.
For each of the repair mechanisms below, in which phase of the cell cycle does the repair mechanism function? What are the key enzymes or genes specifically associated with each mechanism? DNA Polymerase (proofreading) Mismatch Repair Nucleotide Excision Repair Base Excision Repair
DNA polymerase proofreading occurs during the S phase of the cell cycle and the key enzyme used here is DNA polymerase. Mismatch repair occurs during the G2 phase of the cell cycle and the key enzymes used here are MSH2 and MLH1 in eukaryotes and MutS and MutL in prokaryotes. Nucleotide excision repair (NER) occurs during G1 and G2 phases of the cell cycle and the key enzyme used here is excision endonuclease. Base excision repair (BER) occurs during the G1 and G2 phases of the cell cycle and the key enzymes used here are glycosylase and endonuclease.
What eukaryotic polymerase(s) synthesize replicated DNA?
DNA polymerases alpha, delta, and epsilon work together to synthesize both the leading and lagging strands; DNA polymerase delta also fills in the gaps left behind when RNA primers are removed
What eukaryotic polymerase(s) do DNA repair?
DNA polymerases beta and epsilon are important to the process of DNA repair
What are promoters?
DNA region where the transcription initiation takes place; it aids in RNA polymerase binding to DNA
Summarize Darwin's theory of natural selection
Darwin's theory of natural selection argues that chance variations between organisms can help certain organisms survive to reproductive age and produce many offspring, transmitting their variations to the next generation. Thus, natural selection would drive the process of evolution forward, enabling the persistence of characteristics that impart an advantage in the environment. In Darwin's theory, fitness is measure in terms of reproductive success. Through natural selection, organisms may be separated into groups depending on environmental pressures, and these groups can eventually separate to the point of becoming distinct species.
Describe de novo synthesis of cholesterol
De novo synthesis of cholesterol occurs in the liver and is driven by acetyl-CoA and ATP. The citrate shuttle carries mitochondrial acetyl-CoA into the cytoplasm, where synthesis occurs. NADPH (from the PPP) supplies reducing equivalents. Synthesis of mevalonic acid in the smooth ER is the rate-limiting step in cholesterol synthesis and s catalyzed by HMG CoA reductase.
Describe debranching enzyme
Debranching enzyme is a two-enzyme complex that deconstructs the branches in glycogen that have been exposed by glycogen phosphorylase. Debranching enzyme: *Breaks an alpha-1,4 bond adjacent to the branch point and moves the small oligoglucose chain that is released to the exposed ends of the other chain. *Forms a new aplha-1,4 bond. *Hydrolyzes the alpha-1,6 bond, releasing the single residue at the branch point as free glucose. This represents the only free glucose produced directly in glycogenolysis (as opposed to the glucose produced from G1P, which must be converted by a mutase to G6P before it can be converted to glucose via the enzyme glucose-6-phosphotase).
What are defensins?
Defensins are examples of antibacterial enzymes on the skin
Describe the lytic and lysogenic cycles of the virus cycle
Depending on growth conditions and the specific virus, bacteriophages may enter a lytic or lysogenic life cycle. These two phases are similar to the lysis and productive cycle methods of progeny release.
Describe desmosomes
Desmosomes bind adjacent cells by anchoring to their cytoskeletons. Desmosomes are formed by interactions between transmembrane proteins associated with intermediate filaments inside adjacent cells. Desmosomes are primarily found at the interface between two layers of epithelial tissue. Hemidesmosomes have a similar function, but their main function is to attach epithelial cells to underlying structures, especially the basement membrane,
Describe Differentiation of cell on their way to specialization
Differentiation is what occurs when the structure, function, and biochemistry of a cell change to match its determined type. The tissues a stem cell can differentiate into are determined by its potency. *Totipotent cells can differentiate into any cell type *Pluripotent cells can differentiate into any cell type except for those found in the placental structure *Multipotent cells can differentiate into multiple types of cells within a particular group. Ex: Hematoplastic stem cells can become any cell found in blood by not any skin cells
Summary of digestion of carbohydrates
Digestion begins in the mouth: 1. Broken down by amylase in the mouth 2. Broken down by amylase released from the pancreas into the duodenum. 3. Broken down by disaccharidases of the small intestines brush border enzymes into monosaccharides glucose, galactose, and fructose.
Summary of the digestion of fats
Digestion begins in the mouth: 1. Broken down by lipase in the mouth 2. Broken down by lipase released from the pancreas into the duodenum. 3. Broken down by bile released from the gallbladder into the duodenum into free fatty acids
Summary of digestion of proteins
Digestion begins in the stomach: 1. Broken down by pepsin in the stomach 2. Broken down by pancreatic peptidases released into the duodenum. 3. Broken down by dipeptidases and aminopeptidase of the small intestines brush border enzymes into amino acids and di-, tripeptides.
Describe lactose
Disaccharide composed of one molecule of D-galactose and one of D-glucose; linkage between units is "β-" (1--->4)
Describe divergent evolution
Divergent evolution refers to the independent development of dissimilar characteristics in two or more lineages sharing a common ancestor. For example, seal s and cats are both mammals in the order Carnivora, yet they differ markedly in general appearance. These two species live in very different environments and adapted to different selection pressures while evolving.
Describe the lytic cycle
During a lytic cycle, the bacteriophage maximizes the use of the cell's machinery with little regard for the survival of the host cell. Once the host is swollen with new virions, the cell lyses and other bacteria can become infected. Viruses in the lytic phase are said to be virulent.
Describe ketolysis in the brain
During a prolonged fast (longer than one week), the bran begins to derive up to two-thirds of its energy from ketone bodies. In the brain, when ketones are metabolized to acetyl-CoA, pyruvate dehydrogenase is inhibited. Glycolysis and glucose uptake in the brain decreases. This important switch spares essential protein in the body, which otherwise would be catabolized to form glucose by gluconeogenesis in the liver, and allows the brain to indirectly metabolize fatty acids as ketone bodies.
Describe Rh factor and its implications for pregnancy
During childbirth, no matter how good the obstetrician is, women are exposed to a small amount of fetal blood. If a woman is Rh- and her fetus is Rh+, she will become sensitized to the Rh factor, and her immune systems will begin making antibodies against it. This is not a problem for the first child; by the time the mother starts producing antibodies the child has already been born. However, any subsequent pregnancy in which the fetus is Rh+ will present a problem because maternal anti-RH antibodies can cross the placenta and attack the fetal blood cells, resulting in hemolysis of the fetal cells. This condition is known as erythroblastosis fetalis and can be fatal to the fetus. Today, we can use medicine to prevent this condition. There is less concern with ABO mismatching between mother and fetus because these maternal antibodies against AB antigens are of a class called IgM, which does not readily cross he placenta like anti-RH IgG antibodies do.
Describe implantation
During implantation the blastula moves through the fallopian tube to the uterus where it burrows into the endometrium. Once there, the trophoblasts create an interface between the maternal blood supply and the developing embryo. These trophoblast cells also give rise to the chorion, an extraembryonic membrane the develops into the placenta. The trophoblasts will then form chorionic villi which are microscopic finger-like projections that penetrate the endometrium. As these chorionic villi develop into the placenta they support maternal-fetal gas exchange.
Describe the proofreading function of DNA polymerase
During synthesis, the two double-stranded DNA molecules will pass through a part of the DNA polymerase enzyme for proofreading. When the complementary strands have incorrectly paired bases, the hydrogen bonds between the strands can be unstable, and this lack of stability is detected as the DNA passes through this part of the polymerase (the polymerase is pushing on the DNA to test the strength of the strands). The incorrect base is excised and can be replaced with the correct one. The polymerase is able to tell the difference between the daughter and the parent strand thanks to methylation (the parent strand is much more methylated). This system is very efficient, correcting most of the errors put into the sequence during replication. Note: DNA ligase, which closes the gap between Okazaki fragments, lacks proofreading ability. Thus, the likelihood of mutations in the lagging strand is considerably higher than the leading strand.
Describe the G2 stage of the cell cycle
During the G2 stage, the cell passes through another quality control checkpoint. DNA has already duplicated and then the cell checks to ensure that there are enough organelles and cytoplasm for two daughter cells.
When does implantation of an egg occur?
During the blastula stage
Describe the structure of a sarcomere: H-zone, I-band, Z-lines, M-lines, A-band What happens to these structures during contraction?
Each sarcomere is divided into different lines, zones, and bands: *Z-lines define the boundaries of each sarcomere *The M-line runs down the center of the sarcomere, through the middle of the myosin filaments. *The I-band is the region containing exclusively thin filaments *The H-zone contains only thick filaments *The A-band contains the thick filaments in their entirety, including any overlap with thin filaments During contraction, the H-zone, I-band, the distance between Z-lines, and the distance between M-lines all become smaller, whereas the A-band's size remains the same.
Describe male sexual development
During the fetal period (from nine weeks of fertilization until birth), presence of the Y chromosome leads to production of androgens resulting in male sexual differentiation. For the duration of infancy and childhood, androgen production is low. Testosterone, produced by the testses, increases dramatically during puberty and sperm production begins. In order to achieve this, there is a delicate interplay of FS and LH stimulation on two cell types in the testes. The FSH simulates the Sertoli cells and triggers sperm maturation. The LH causes the interstitial cells to produce testosterone. Testosterone not only develops and maintains the male reproductive system, but also results in the development of secondary sexual characteristics such as facial and axillary hair, deepening of the voice, and increased muscle and bone mass. Testosterone remains high into adulthood and declines as men age. This hormone exerts negative feedback on the hypothalamus and anterior pituitary so that production is kept within appropriate range.
During what stage of metabolic states is there the greatest decrease in the circulating concentration of insulin?
During the postabsorptive stage, there is the greatest decrease in insulin levels. The concentrations of the counterregulatory hormones (glucose, cortisol, epinephrine, norepinephrine, and growth hormones ) begin to rise.
What happens in apoptosis?
During the process of apoptosis, the cell undergoes changes in morphology and divides into many self contained protrusions called apoptic blebs which can then be broken apart into apoptic bodies and digested by other cells. This allows recycling of materials. Because the blebs are contained by a membrane, this also prevents release of potentially harmful substances into the extracellular environment. Note: This is different from necrosis, which is a process of cell death in which a cell dies as a result of injury. IN necrosis, internal substances can be leaked.
What is the formula for catalytic efficiency?
E= Kcat/Km
What is the Nernst equation for calculating membrane potential?
E= RT/zF ln ([ion]outside/([ion]inside) = 61.5/z log ([ion]outside/([ion]inside) *where R is the ideal gas constant, T is temperature in kelvins, z is the charge of the ion, and F is Faraday's constant (96,485 C/ mol e-). The simplification to 61.5 in the numerator assumes body temperature
How does tRNA get loaded with an amino acid?
Each type of amino acid is activated by a different aminoacyl-tRNA synthetase that requires two high-energy bonds from ARP, implying that the attachment of the amino acid is an energy-rich bond. The aminoacyl-tRNA synthetase transfers the activated amino acid to the 3' end of the correct tRNA--each tRNA has a CCA nucleotide sequence that indicates where the amino acid binds. The high energy aminoacyl-tRNA bond will be used to supply the energy needed to create a peptide bond during translation.
Describe the process of elongation in translation
Elongation is a three-step cycle that is repeated for each amino acid added to the protein after the initiator methionine. During elongation, the ribosome moves in the 5' to 3 direction along the mRNA, synthesizing the protein from its amino (N-) terminus to its carboxyl (C-) terminus. The ribosome contains three very important binding sites: *The A site holds the incoming aminoacyl-tRNA complex. This is the next amino acid that is being added to the growing chain and is determined by the mRNA codon within the A site. *The P site holds the tRNA that carries the growing polypeptide chain. It is also where the first amino acid (methionine) binds because it is starting the polypeptide chain. A peptide bond is formed as the polypeptide is passed from the tRNA in the P site to the tRNA in the A-site. This requires peptidyl transferase, an enzyme that is part of the large subunit. GTP is used for energy during the formation of this bond. *The E site is where the now inactivated (uncharged) tRNA pauses transiently before exiting the ribosome. As the now-uncharged tRNA enters the E site, it quickly unbinds from the mRNA and is ready to be recharged. Elongation factors (EF) assist by locating and recruiting aminoacyl-tRNA along with GTP, while helping to removed GDP once the energy has been used.
Describe embedded proteins
Embedded proteins are associated with only the interior (cytoplasmic) or exterior (extracellular) surface of the cell membrane. They are most likely part of a catalytic complex or involved in cellular communication.
Describe endocrine signaling
Endocrine signaling involves the secretion of hormones directly into the bloodstream. The hormones travel to distant target tissues, where they bind to receptors and induce a change in gene expression or cell function.
Describe endorphins
Endorphins decrease the perception of pain. For example, after completing a marathon, many people will say they are on an endorphin "high" or "rush". Endorphins mask the pain from having run 26.2 miles and can even induce a sense of euphoria.
Describe enthalpy
Enthalpy measures the overall change in heat of a system during a reaction. At constant pressure and volume, enthalpy (change in H) and thermodynamic heat exchange (Q) are equal
What are mutases?
Enzymes that move a functional group from one place in a molecule to another. For example 1,3BPG vs 2,3BPG
Explain the difference between esterification and glycoside formation
Esterification is the reaction by which a hydroxyl group reacts with either a carboxylic acid or a carboxylic acid derivative to form an ester. Glycoside formation refers to the reaction between an alcohol and a hemiacetal (or hemiketal) group on a sugar to yield an alkoxy group.
Describe the ovulation phase of the ovarian cycle
Estrogen can have both positive and negative feedback effects: Late in the follicular phase, the developing follicles secrete higher and higher concentrations of estrogen. Eventually estrogen concentrations reach a threshold what paradoxically results in positive feedback and GnRH, LH, and FSH levels spike. The surge in LH causes ovulation (the release of the ovary into the abdominal cavity).
What is the acronym for the roles of estrogen and progesterone?
Estrogen establishes and progesterone protects In adults estrogens lead to the thickening of the lining of the uterus (endometrium) each month in preparation of the implantation of the zygote. Progesterone is secreted by the corpus luteum (the remains of the ovarian follicle following ovulation) in response to LH. Progesterone is involved in the development and maintenance of the endometrium but not in the initial thickening of the endometrium (that's the role of estrogen).
Describe estrogen's role in female development
Estrogens are secreted in response to FSH and result in the development and maintenance of the female reproductive system and female secondary characteristics. In the embryos, estrogens stimulate development of the reproductive tract. In adults estrogens lead to the thickening of the lining of the uterus (endometrium) each month in preparation of the implantation of the zygote.
Describe the primary germ layers
Eventually, some cells will migrate into what remains of the blastocoel. THis establishes thee layers of cells the the primary germ layer. This consists of: *The ectoderm: aka "atracto"derm; this makes up things that attract us to others such as cosmetic features and smarts *The mesoderm- aka "means"oderm; this provides us with the means of getting around as an organism (such as bones and muscles), the means of getting around in the body (like blood vessels), and the means of getting around (such as the gonads) *The endoderm- which does the lining of "endernal" (internal) organs (such as the digestive and respiratory tract and accessory organs attached to these systems)
What's the difference between exocrine and endocrine glands?
Exocrine glands secrete their products through ducts; endocrine glands release their products into the bloodstream.
What is exocytosis?
Exocytosis occurs when secretory vesicles fuse with the membrane, releasing A BUNCH of material from inside the cell to the extracellular environment. Exocytosis is important in the nervous system and intercellular signaling. For instance, exocytosis of neurotransmitters from synaptic vesicles is a crucial aspect of neuron physiology.
What is ERV?
Expiratory Reserve Volume: the volume of additional air that can be forcibly exhaled after a normal exhalation
Describe Fructose-1,6-Bisphophatase
F-1,6-bisphoshatase in the cytoplasm is a key control point of gluconeogenesis and represents the rate-limiting step of the process. It reverses the action of PFK-1, the rate-limiting step of glycolysis, by removing phosphate from F1,6BP to produce F6P. F-1,6-bisphosphatase is activated by ATP and inhibited by AMP. It is also inhibited by the presence of F2,6BP
Describe ATP synthase.
F0 functions as an ion channel, so protons travel through F0 along their gradient back into the matrix. As this happens, a process called chemiosmotic coupling allows the chemical energy of the gradient to be harnessed as a means of phosphorylating ADP, thus forming ATP. In other words, the ETC generates a high concentration of protons in the intermembrane space; the protons then flow through the f0 ion channel of AP synthase back into the matrix. AS this happens, the other portion of ATP synthase, which is called the F1 portion, utilizes the energy released from this electrochemical gradient to phosphorylate ADP to ATP.
What hormones are released from the anterior pituitary?
FLAT PeG FSH LH ACTH TSH (thyroid-stimulating hormone) Prolactin (inhibited by prolactin inhibiting factor) endorphins Growth Hormone Note: the four hormones in FLAT are all tropic hormones, while the three hormones in PEG are all direct hormones.
How are vitamins absorbed in the jejunum and ileum?
Fat-soluble vitamins dissolve directly into chylomicrons to enter the lymphatic circulation. Failure to digest and absorb fat properly, which can be due to pathologies in the liver, gallbladder, pancreas, or small intestine, may lead to deficiencies of fat-soluble vitamins. Water-soluble vitamins are taken up, along with water, amino acids, and carbohydrates, across the endothelial cells of the small intestine, passing directly into the plasma.
Why are fatty acids used to create ketone bodies instead of creating glucose?
Fatty acid degradation results in large amounts of acetyl-CoA, which cannot enter the gluconeogenic pathway to produce glucose. Only odd-numbered fatty acids can act as a source of carbon for gluconeogenesis; even then, only the final malonyl-CoA molecule can be used. Energy is packaged into ketone bodies for consumption by the brain and muscles.
Describe fatty acid synthase
Fatty acid synthase is more appropriately called palmitate synthase because palmitate is the only fatty acid that humans can synthesize de novo. Fatty acid synthase is a large multienzyme complex found in the cytosol that is rapidly induced in the liver following a meal high in carbohydrates because of elevated insulin levels. The enzyme complex contains an acyl carrier protein (ACP) that requires pantothenic acid (vitamin B5). NADPH is also required to reduce the acetyl groups added to the fatty acid. Eight acetyl-groups are required to produce palmitate (16:0)
How do fatty acid synthesis and beta oxidation relate?
Fatty acid synthesis and beta-oxidation are reverse processes. Both involve transport across the mitochondrial membrane, followed by a series of redox reactions, but always in the opposite direction of one another. Understanding one process will enable you to answer questions about both pathways.
Describe fatty acids
Fatty acids are carboxylic acids that contain a hydrocarbon chain and terminal phospholipid group
Describe the structure of fatty acids
Fatty acids are long-chain carboxylic acids. The carboxyl carbon is carbon 1, and carbon 2 is referred to as the alpha-carbon. Fatty acids found within the body occur as salts that are capable of forming micelles or are esterified to other compounds, such as membrane lipids.
Why can't the brain use fatty acids as a fuel source?
Fatty acids cannot cross the BBB
How do fatty acids with an odd number of carbons undergo beta-oxidation?
Fatty acids with an odd number of carbon atoms undergo beta-oxidation in the same manner as even-numbered carbon fatty acids for the most part. The only difference is observed during the final cycle, where even-numbered fatty acids for the most part yield two acetyl CoA molecules (from the four-carbon remaining fragment), and odd-numbered fatty acids yield one acetyl-CoA and one propionyl-CoA (from the five-carbon remaining fragment. Propionyl-CoA is then converted to methylmalonyl-CoA by propionyl-CoA carboxylase, which requires biotin (vitamin b7). Methylmalonyl-CoA is then converted into succinyl-CoA by methylmalonyl-CoA mutase, which requires cobalamin (vitamin B12). Succinyl-CoA is a citric acid cycle intermediate and can also be converted to malate to enter the gluconeogenic pathway in the cytosol. Odd-carbon fatty acids thus represent an exception o the rule that fatty acids cannot be converted to glucose in humans.
Why must pyruvate undergo fermentation for glycolysis to continue?
Fermentation must occur to regenerate NAD+, which is in limited supply in cells. Fermentation generates no ATP or energy carriers, it merely regenerates the coenzymes needed in glycolysis.
Where does fertilization occur?
Fertilization usually takes place in the widest part of the fallopian tube called the ampulla.
How does fetal hemoglobin differ from adult hemoglobin?
Fetal hemoglobin (HbF) has a greater affinity for oxygen than maternal (adult) hemoglobin (HbA)
How is cholesterol synthesis regualted?
First, increased levels of cholesterol can inhibit further synthesis by a feedback inhibition mechanism. Next, insulin promotes cholesterol synthesis. Control over de novo cholesterol synthesis is also dependent on regulation of HMG-CoA reductase gene expression in the cell.
Describe the pathway of ejaculation
Firstly, the testes have two functional components the seminiferous tubules and the interstitial cells of Leydig. Sperm are produced in the highly coiled seminiferous tubules, where thy are nourished by Sertoli cells. The cells of Leydig secrete testosterone and other male sex hormones (androgens). As sperm are formed, they are passed to the epididymis where their flagella gain motility and they become capable of fertilization. They are then stored until ejaculation. During ejaculation, sperm travel through the vas deferens and enter the ejaculatory duct at the posterior edge of the prostate gland. The two ejaculatory ducts then fuse to form the urethra which carries sperm through the penis as they exit the body. Seminiferous tubules Epididymis Vans Deferens Ejaculatory Duct (N) Urethra Penis
Describe flippases
Flippases are responsible for the movement of phospholipids between the layers of the plasma membrane because it is otherwise energetically unfavorable.
Describe lysosomes
Floating garbage disposal of the cell --responsible for the breakdown of proteins Recycle cellular waste Have lots of enzymes inside
Describe what happens as food enters the duodenum
Food leaves the stomach through the pyloric sphincter and enters into the duodenum. The presence of chyme in the duodenum causes the release of brush-border enzymes like disaccharidases (maltase. isomaltase. lactase, and sucrase) and peptidases (including dipeptidase). The duodenum also secretes enteropeptidase which is involved in the activation of other digestive enzymes from the accessory organs of digestion. Finally, it secrets hormones like secretin and cholecystokinin (CCK) into the blood stream.
Describe the cell cyle
For actively dividing cells the cell cycle has 4 phases: G1, S, G2, and M. The first three stages (G1, S, and G2) are known collectively as interphase, making interphase the longest part of the cell cycle. Cells that do not divide spend all of their time in an offshoot of G1 called G0. During the G0 stage, the cell is simply living and carrying out its functions without any preparation for division.
How does glucose cause release of insulin?
For glucose to promote insulin secretion, it must not only enter the beta-cell but also be metabolized, increasing intracellular ATP concentration. Increased ATP leads to calcium release in the cell, which promotes exocytosis of preformed insulin from intracellular vesicles.
What are the patterns of Mendelian inheritance?
Four features: *Autosomal Dominant Inheritance. *Autosomal Recessive Inheritance. *X-linked Inheritance. *Complex Inheritance.
What are free fatty acids?
Free fatty acids are unesterified fatty acids that travel in the bloodstream. Salts of free fatty acids are soaps and can be synthesized in saponification.
Describe fructose metabolism
Fructose is found in honey and fruit and as part of the disaccharide sucrose (common table sugar). Sucrose is hydrolyzed by the duodenal brush-border enzyme sucrase, and the resulting monosaccharides, glucose and fructose, are absorbed into the hepatic portal vein. The liver phosphorylates fructose using fructokinase to trap it in the cell. The resulting fructose 1-phosphate is then cleaved into glyceraldehyde and DHAP by aldolase B. Smaller amounts are metabolized in renal proximal tubules
What is the rate limiting enzyme of gluconeogenesis?
Fructose-1-6-bisphosphatase
What is the sensor for insulin release?
GLUT2 and glycolytic enzyme glucokinase
Describe the GLUT2 transporter
GLUT2 is a low-affinity transporter in hepatocytes and pancreatic cells. After a meal, blood traveling through the hepatic portal vein from the intestine is rich in glucose. GLUT2 captures the excess glucose primarily for storage. When the glucose concentration drops below the Km for the transporter, much of the remainder bypasses the liver and enters the peripheral circulation. The Km of GLUT2 is quite high (15mM). This means that the liver will pick up glucose in proportion to its concentration in the blood (first-order kinetics). In other words, the lover will pickup excess glucose and store it preferentially after a meal, when glucose levels are high. Note: remember that the Km is the concentration of substrate when an enzyme is active at half D. The lower the Km, the higher the enzyme's affinity for the substrate.
Describe GLUT4
GLUT4 is in adipose tissue and muscle and responds to the glucose concentration in peripheral blood. The rate of glucose transport in these two tissues is increased by insulin, which stimulates the movement of additional GLUT 4 transporters to the membrane via a mechanism involving exocytosis. The Km of GLUT4 is close to the normal glucose levels in blood (5 mM). This means that the transporter is saturated when blood glucose levels are just a bit higher than normal. When a person has high blood sugar concentrations, these transporters will still only permit a constant rate of glucose influx because they will be saturated. Then how can cells with GLUT5 transporters increase their intake of glucose? By increasing the number of GLUT4 transporters on their surface.
Describe gangliosides
Gangliosides are glycolipids that have polar head groups composed of oligosaccharides with one or more N-acetylneuraminic acid (NANA; also called sialic acid) molecules at the terminus and a negative charge. These molecules are also considered glycolipids because they have a glycosidic linkage and no phosphate group. Gangliosides play a major role in cell interaction, recognition, and signal transduction. Gangliosides are the "gangly" sphingolipids with the most complex structure and functional groups (oligosaccharides and NANA) in all directions
Describe gap junctions
Gap junctions allow for direct cell-cell communication and are often found in small bunches together. Gap junctions are also called connexons and are formed by the alignment and interaction of pores composed of six molecules of connexin. They permit the movement of water and some solutes directly between cells. Proteins are generally not transferred through gap junctions.
Describe gastric juice
Gastric juice is a combination of secretions from two cell types in the gastric glands: chief cells and parietal cells. The chief cells secrete pepsinogen. This is the inactive, zymogen form of pepsin, a proteolytic enzyme. Hydrogen ion sin the stomach, secreted by parietal cells as hydrochloric acid, cleave pepsinogen to pepsin. Pepsin digests proteins by cleaving peptide bonds near aromatic amino acids, resulting in short peptide fragments. Because pepsin is activated by the acidic environment, it follows that pepsin is most active at low pH. Note: in addition to HCl, parietal cells secrete intrinsic factor, a glycoprotein involved in the proper absorption of vitamin B12.
Describe gel electrophoresis and southern blotting in relation to DNA
Gel electrophoresis is a technique used to separate macromolecules, such as DNA and proteins, by size and charge. All molecules of DNA are negatively charged because of the phosphate groups in the background of the molecule, so all DNA strands will move towards the anode of an electrochemical cell. The preferred gel for DNA electrophoresis is agarose gel, and --just like proteins in polyacrylamide gel -- the longer the DNA strand, the slower it will migrate in the gel. Gel electrophoresis is often used while performing a Southern blot. A Southern blot is used to detect the presence and quantity of various DNA strands in a sample. DNA is cut by restriction enzymes and then separated by gel electrophoresis. The DNA fragments are then carefully transferred to a membrane, retaining their separation. The membrane is then probed with many copies of a single-stranded DNA sequence. The probe will bind to its complementary sequence and form double-stranded DNA. Probes are labeled with radioisotopes or indicator proteins, both of which can be used to indicate the presence of a desired sequence.
Describe genetic drift
Genetic drift refers to changes in the composition of the gene pool due to chance. Genetic drift tends to be more pronounced in small populations. It results in the REDUCTION in genetic diversity
Describe geneitc maps
Genetic maps represent the relative distance between genes on a chromosome. By convention, one map unit or centimorgan corresponds to a 1 percent chance of recombination occurring between two genes. Thus, if two genes were 25 map units apart, we would expect 25 percent of the total gametes examined to show recombination somewhere between these two genes.
What are the nonpolar amino acids?
George Likes Ian's Very A Polar Molecules Glycine; Leucine; Isoleucine; Valine; Alanine; Proline; Methionine
Describe ghrelin and orexin
Ghrelin is secreted by the stomach in response to signals of an impending meal. Sight, sound, taste, and especially smell all act as signals for its release. Ghrelin increases appetite and also stimulates secretion of orexin. Orexin further increases appetite and is also involved in alertness and the sleep-wake cycle. Note: hypoglycemia is also a trigger for orexin release
Draw Glutamine
Gln; Q
What causes glucocorticoid release?
Glucocorticoid release is under the control of adrenocorticotropic hormone (ACTH). Corticotropin-releasing factor (CRF) from the hypothalamus promotes release of adrenocorticotropic hormone (ACTH) from the anterior pituitary, which promotes release of glucocorticoids from the adrenal cortex.
Describe glucocorticoids
Glucocorticoids are steroid hormones that regulate glucose levels. In addition, these hormones also affect protein metabolism. The most important glucocorticoids are cortisol and cortisone. These hormones raise blood glucose by increasing gluconeogenesis and decreasing protein synthesis. Cortisol and cortisone can also decrease inflammation and immunologic responses. Cortisol is known as a stress hormone because it is released in times of physical or emotional stress. This increases blood sugar and provides a ready source of fuel in case the body must react quickly to a dangerous stimulus. Note: Glucocorticoid release is stimulated by ACTH.
How does cortisol work?
Glucocorticoids, especially cortisol, are secreted with many forms of stress, including exercise, cold, and emotional stress. Cortisol is a steroid hormone that promotes the mobilization of energy stores through the degradation and increased delivery of amino acids and increased lipolysis. Cortisol also elevates blood glucose levels, increasing glucose availability for nervous tissue through two mechanisms. First, cortisol inhibits glucose uptake in most tissues (muscle, lymphoid, and fat) and increases hepatic output of glucose via gluconeogenesis, particularly from amino acids. Second, cortisol has a permissive function that enhances the activity of glucagon, epinephrine, and other catecholamines.
What is the difference between glucogenic amino acids and ketogenic amino acids?
Glucogenic amino acids (all except leucine and lysine) can be converted into intermediates that feed into gluconeogenesis, while ketogenic amino acids can be converted into ketone bodies, which can be used as an alternative fuel, particularly during periods of prolonged starvation.
Describe glucokinase
Glucokinase phosphorylated glucose into G6P and traps glucose in liver and pancreatic cells, and works with GLUT 2 as part of the glucose sensor in beta-islet cells. In liver cells, it is induced by insulin. It is irreversible.
What is the first step of glycolysis?
Glucose enters the cell by facilitated diffusion or active transport; in either case, glucokinase and hexokinase convert glucose into glucose 6-phosphate. Because the GLUT transporters are specific for glucose (not phosphorylated glucose), the glucose gets trapped inside the cell and cannot leak out. Note: Hexokinase is widely distributed in tissues (and thus has a low Km) and is inhibited by its product, G6P. Glucokinase is found only in liver cells and pancreatic beta-islet cells (and thus has a high Km); in the liver, glucokinase is induced by insulin
Describe Glucose-6-phosphatase
Glucose-6-phosphatase is found only in the lumen of the endoplasmic reticulum in liver cells. Glucose 6-phosphate is transported into the ER, and free glucose is transported back into the cytoplasm, from where it can diffuse out of the cell using GLUT transporters.GLucose-6-phosphatase is used to circumvent glucokinase and hexokinase, which convert glucose to G6P. Note: The absence of glucose-6-phosphatase in skeletal muscle means that muscle glycogen cannot serve as a source of blood glucose and rather is for use only within the muscle.
Draw and describe Glycine
Gly;G Glycine has an H as its R group and thus is achiral. It is also the smallest amino acid
How does Glycerol 3-phosphate enter gluconeogenesis?
Glycerol 3-Phosphate is converted to DHAP by G3P phosphate dehydrogenase
Describe Glycerophospholipids and draw an example of one
Glycerophospholipids, aka phosphoglycerides, are phospholipids that contain a glycerol backbone bonded by ester linkages to two fatty acids and by a phosphodiester linkage to a highly polar head group. Note: Because the head group determines the membrane surface properties, glycerophospholipids are named according to their head group. For example, phosphatidylcholine is the name of a glycerophospholipid with a choline head group, and phosphatidylethanolamine is one with an ethanolamine head group. The head group can be positively charged, negatively charged, or neutral.
What is the role of glycine in peptide squences?
Glycine helps put kinks throughout a helix due to so little hindrance
Describe glycogen
Glycogen is a carbohydrate storage unit in animals. It is similar to starch, except that it has more alpha-1,6 glycosidic bonds (approximately one for every 10 glucose molecules, while amylopectin has approximately one for every 25), which makes it a highly branched compound. This branching optimizes the energy efficiency of glycogen and makes it more soluble in solution, thereby allowing more glucose to be stored in the body. Also, its branching pattern allows enzymes that cleave glucose from glycogen, such as glycogen phosphorylase, to work on many sites within the molecule simultaneously.
What is the structure of glycogen?
Glycogen is made up of a core protein of glycogenin with linear chains of glucose emanating out from the center, connected by alpha-1,4 glycosidic links. Some of these chains are branched, which requires alpha-1,6 glycosidic links.
What is the rate-limiting enzyme of glygoenolysis?
Glycogen phosphorylase
Describe glycogen phosphorylase
Glycogen phosphorylase breaks alpha-1,4 bonds, releasing G1P from the periphery of the granule. It cannot break alpha-1,6 bonds and therefore stops when it nears the outermost branch points. Glycogen phosphorylase is activated by glucagon in the liver, so that glucose can be provided for the rest of the body. In skeletal muscle, it is activated by AMP and epinephrine, which signal that the muscle is active and requires more glucose. It is inhibited by ATP.
Describe glycogen phosphorylase
Glycogen phosphorylase functions by cleaving glucose from the nonreducing end of a glycogen branch and phosphorylating it, thereby producing glucose 1-phosphate, which plays an important role in metabolism.
Describe glycogen synthase
Glycogen synthase is the rate limiting enzyme of glycogen synthesis and forms the alpha-1,4 glycosidic bond found in the linear chains of the granule. It is stimulated by G6P and insulin. It is inhibited by epinephrine and glucagon through a protein kinase cascade that phosphorylated and inactivated the enzyme.
Describe glycogenesis
Glycogenesis is the synthesis of glycogen granules. It begins with a core protein called glycogenin. Glucose addition to a granule begins with glucose 6-phosphate, which is converted into glucose 1-phosphate. This glucose 1-phosphate is then activated by coupling to a molecule of UDP, which permits its integration into the glycogen chain by glycogen synthase. This activation occurs when glucose 1-phosphate interacts with UTP, forming UDP-glucose and pyrophosphate (PPi).
Describe glycolysis
Glycolysis is a cytoplasmic pathway that converts glucose into two pyruvate molecules, releasing a modest amount of energy captured in two substrate level phosphorylations and one oxidation reaction. If a cell has mitochondria and oxygen, the energy carriers produced in glycolysis (NADH) can feed into the aerobic respiration pathway to generate energy for the cell. If either mitochondria or oxygen is lacking (such as in RBC or exercising skeletal muscle respectively ), glycolysis may occur anaerobically although some available energy is lost.
What is the benefit of the segregation of homologous chromosomes and independent assortment of alleles?
Greater genetic diversity in offspring
What is the function of growth hormone?
Growth hormone promotes growth of bone and muscle and shunts glucose to these tissues. It raises blood glucose concentrations.
Order the lipoproteins from greatest percentage of protein to least percentage of protein. Which are involved primarily in triacylglycerol transport?
HDL > IDL> LDL > VLDL > chylomicrons VLDL and chylomicrons are involved primarily in triacylglycerol transport.
Describe HDL
HDL is synthesized in the liver and intestines and is released as dense, protein-rich particles into the blood. HDL contains apolipoproteins used for cholesterol recovery --that is, the cleaning up of excess cholesterol from blood vessels for excretion. HDL also delivers some cholesterol to steroidogenic tissues and transfers necessary apolipoproteins to some of the other lipoproteins.
What are the functions of HDL
HDL picks up cholesterol accumulating in blood vessels, delivers cholesterol to liver and steroidogenic tissues, and transfers apolipoproteins to other lipoproteins.
What are the gastric secretions? (things secreted into the stomach)
HIPGLOM HCl- secreted by parietal cells of the stomach Intrinsic factor- protection factor of VitB12 from pepsins that come from parietal cells of the stomach Pepsinogens- proteases that come from chief cells *Gastrin- it is secreted by antral G-cells into the blood, it acts on parietal cells to increase HCl secretion (happens as long as chyme is present) Lipase-will hydrolyze lipids; they come out of chief cells Others- histamine is one example, it acts on the parietal cells to increase HCl (it is the main reason that parietal cells produce HCl); another example is somatostatin which serves to decrease HCl locally Mucus- will lubricate the gastric epithelial cells to protect them by trapping HCO3- to buffer against H+ from HCl *Gastrin goes into the blood while everything else listed goes into the lumen
Under what conditions is HMG-CoA reductase most active? In what cellular region does it exist?
HMG-CoA reductase is most active in the absence of cholesterol and when stimulated by insulin. Cholesterol reduces the activity of HMG-CoA reductase, which is located in the smooth endoplasmic reticulum.
Describe Anaphase 1 of meiosis
Homologous pairs separate and are pulled to opposite poles of the cell. A process known as disjunction, and it accounts for Mendel's first law (the law of segregation). During disjunction, each chromosome of paternal origin separates (or disjoins) from its homolog of maternal origin and either chromosome can end up in either daughter cell. This separation of the two homologous chromosome si s referred to as segregation.
Describe helper T cells
Helper T-cells (Th), also called CD4+ T-cells, coordinate the immune response by secreting chemicals known as lymphokines. These molecules are capable of recruiting other immune cells (such as plasma cells, cytotoxic T-cells, and macrophages) and increasing their activity. The loss of these cells, as occurs in HIV infection, prevents the immune system from mounting an adequate response to infection; in advanced HIV infection, also called AIDS, even weak pathogens can cause devastating consequences as opportunistic infections. Because MHC-II present exogenous antigens, CD4+ T-cells are most effective against bacterial, fungal, and parasitic infections.
Describe glycoside formation
Hemiacetals react with alcohols to form acetals. The anomeric hydroxyl group is transformed into an alkoxy group, yielding a mixture of alpha- and beta- acetals (with water as a leaving group). The resulting carbon-oxygen (C-O) bonds are called glycosidic bonds, and the acetals formed are glycosides. Equivalent reactions happen with hemiketals, forming ketals. Disaccharides and polysaccharides form as a result of glycosidic bonds between monosaccharides. Glycosides derived from furanose rings are referred to as furanosides and those derived from pyranose rings are called pyranosides. Note: glycoside formation is a dehydration reaction; thus breaking a glycosidic bond requires hydrolysis.
Describe the G2/M checkpoint
Here the cell is mainly concerned with ensuring that it has achieved adequate size and that the organelles have been properly replicated to support two daughter cells. Protein p53 plays a role here
Describe hexokinase
Hexokinase phosphorylated glucose to form G6P, trapping glucose in the cell. It is inhibited by G6P. It is irreversible.
What are Hfr cells?
Hfr (high frequency recombination) cells are bacterial cells that integrated their sex factor into their genome via transformation and are now trying to replicate and pass their entire genome to an F- cell. Note: The conjugation bridge typically breaks before the full genome can be transferred.
Describe metaphase 1 of meiosis
Homologous pairs (tetrad) line up at the metaphase plate and each pair attaches to a separate spindle fiber by its kinetochore.
How do hormonal controls of glycogen metabolism differ from allosteric controls?
Hormonal controls are coordinated to regulate the metabolic activity of the entire organism, while allosteric controls can be local or systemic. The modification of the enzymes of glycogen metabolism by insulin and glucagon is either through phosphorylation or dephosphorylation, both of which modify covalent bonds.
What are the irreversible steps of glycolysis?
How Glycolysis Pushes Forward the Process: Kinases Hexokinase Glucokinase PFK-1 Pyruvate Kinase
Describe hybridization
Hybridization is the joining of complementary base pair sequences. This can be DNA-DNA recognition or DNA-RNA recognition. This technique uses two single-stranded sequences and is a vital part of polymerase chain reaction and Southern blotting.
What are hydrocarbons?
Hydrocarbons are compounds that contain only carbon and hydrogen atoms
Describe hydrostatic pressure
Hydrostatic pressure is the force per unit area that blood exerts against the vessel walls. This is generated by the contraction of the heart and the elasticity of the arteries, and can be measured upstream in the large arteries as blood pressure. Hydrostatic pressure pushed fluid out of the blood stream into the interstitium through the capillary walls, which are somewhat leaky by design.
how does the ABO blood system work?
IA and IB are codominant while i (type O blood) is recessive
What are the functions of IDL
IDL (remnants of VLDL) picks up cholesteryl esters from HDL to become LDL. It is picked up by the liver
Describe summation and tetanus in muscles
If a muscle fiber is exposed to frequent and prolonged stimulation, it will have insufficient time to relax. The contractions will combine, become stronger, and more prolonged. This is known as frequency summation. If the contractions become so frequent that the muscle is unable to relax at all, this is known as tetanus. Prolonged tetanus will result in muscle fatigue.
How do we name a molecule if it has an alcohol that is not of highest priority?
If an alcohol is not the highest priority substituent, it is named as a hydroxyl substituent: "hydroxy-"
Describe the action of the female hormones when pregnancy takes place
If fertilization has occurred, the resulting zygote will develop into a blastocyst that will implant in the uterine lining and secrete human chorionic gonadotropin (hcG), and analog of LH (it looks very similar chemically and can stimulate LH receptors). This maintains the corpus luteum. hcG is crucial during the first trimester development because the estrogen and progesterone secreted by the corpus luteum jeep the uterine lining in place. By the second trimester, hcG levels decline because the placenta has grown to sufficient size to secrete enough estrogen and progesterone by itself. The high levels of estrogen and progesterone continue to serve as negative feedback on GnRH secretin.
When is a cell hypotonic? How will water move? What about hypertonic?
If the concentration of solutes inside a cell is higher than than the surrounding solution, the solution is said to be hypotonic; such a solution will cause a cell to swell as water rushes in, sometimes to the point of bursting (lysing). A solution that is more concentrated than the cell is termed a hypertonic solution, and water will move out of the cell.
Describe calcitonin
If we were to examine thyroid tissue under a light microscope, we would see two distinct cell populations within the gland. Follicular cells produce thyroid hormones and C-cells (also called parafollicular cells) produce calcitonin. Calcitonin decreases plasma calcium levels in three ways: *by increasing calcium excretion from the kidneys *by decreasing calcium absorption from the gut *by increasing storage of calcium in the bone (by promoting bone formation High levels of calcium in the blood stimulate secretion of calcitonin from the C-cells
Anderson's disease (glycogen storage disease type IV) is a condition characterized by a deficiency in glycogen branching enzyme. The absence of this enzyme would cause what?
In Anderson's disease, glycogen is less branched than normal, thereby inducing lower solubility of glycogen--branches reduce the interactions between adjacent chains of glycogen and encourage interactions with the aqueous environment. The smaller number of branches also means that glycogen phosphorylase has fewer terminal glucose monomers on which to act, making enzyme activity slower than normal overall. Finally, without branches, the density of glucose monomers cannot be as high; therefore, the total glucose stored is lower than normal.
Describe a polysynaptic reflex arc.
In a polysynaptic reflex arc, there is at least one interneuron between the sensory and motor neurons -- a sensory neurons may fire directly onto a motor neuron, but interneurons are used as well (these interneurons fire onto other motor neurons).
Describe active immunity
In active immunity, the immune system is stimulated to produce antibodies against a specific pathogen. The means by which we are exposed to this pathogen may be natural or artificial. Through natural exposure, antibodies are generated by B-cells once an individual becomes infected. Artificial exposure (through vaccines) also results in the production of antibodies however, the individual never experiences true infection. Instead, he or she receives nan injection or intranasal spray containing an antigen that will activate B-cells to produce antibodies to fight the specific infection. The antigen may be a weakened or killed form of the microbe, or it may be a part of the microbe's protein structure.
How are bacteriophages different from regular viruses in terms of structure?
In addition to a capsid, bacteriophages contain a tail sheath and tail fibers. The tail sheath acts like a syringe injecting genetic material into a bacterium. The tail fibers help the bacteriophage recognize and connect to the right host cells.
What is the difference between complete regeneration and incomplete regeneration?
In complete regeneration, lost or damaged tissues are replaced with identical tissues. In incomplete regeneration, the newly formed tissue is not identical in structure or function to the tissue that has been injured or lost
Describe glycolysis in red blood cells
In erythrocytes (red blood cells), anaerobic glycolysis represents the only pathway for ATP production, yielding a net 2 ATP per glucose. Red blood cells have bisphosphoglycerate mutase which produces 2,3BPG from 1,3BPG in glycolysis. 2,3BPG binds allosterically to the beta-chains of hemoglobin A (HbA) and decreases its affinity for oxygen. This effect of 2,3BPG results in a right shift in the oxygen dissociation curve. The rightward shift in the curve is sufficient to allow unloading of oxygen in tissues but still allows 100% saturation in the lungs. An abnormal increase in erythrocyte 2,3BPG (as in being in high altitudes over 24 hours), might shift the curve far enough so that HbA is not fully saturated in the lungs.
open reading frame
from start codon to stop codon
How many polymerases are found in eukaryotes?
In eukaryotes there are three types of RNA polymerases, but only one is involved in the transcription of mRNA: *RNA polymerase I is located in the nucleolus and synthesizes rRNA *RNA polymerase II is locate d in the nucleus and synthesis hnRNA (pre-processed mRNA) and some small nuclear RNA (snRNA) *RNA polymerase III is located in the nucleus and synthesizes tRNA and some rRNA
What is one major difference between eukaryotic mRNA and prokaryotic mRNA?
In eukaryotes, mRNA is monocistronic, meaning that each mRNA molecule translates into only one protein product. Thus, in eukaryotes, the cell has a different mRNA molecule for each of the thousands of different proteins made by the cell. In prokaryotes, mRNA may be polycistronic, and starting the process of translation at different locations in the mRNA can result in different proteins.
Describe inducible operon systems
In inducible systems, the repressor is bonded tightly to the operator system and thereby acts as a roadblock--RNA polymerase is unable to get from the promoter to the structural gene because the repressor is in the way. Such systems --in which the binding of a protein reduces transcriptional activity -- are called negative control mechanisms. TO remove the block, an inducer must bind the repressor protein so that RNA polymerase can move down the gene. An example of this is the lac operon
What are the key differences between mitosis and meiosis in terms of: *ploidy *occurrence * homologous pairing *and crossing over
In mitosis, cells remain diploid (2n ->2n) while in meiosis cells end up haploid (2n-> n). Mitosis occurs in all dividing cells except sex cells while meiosis occurs only in sex cells In mitosis, the homologous chromosomes do not pair where as in meiosis they do There is no crossing over in mitosis but it does happen in meiosis
How many capillary beds does blood pass through before returning to the heart?
In most cases, blood will pass through only one capillary bed before returning to the heart. However, there are three portal systems in the body, in which blood will pass through two capillary systems before returning to the heart: In the hepatic portal system, blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver. In the hypophyseal portal system, blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary to allow for paracrine secretion of releasing hormones. In the renal portal system, blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta.
What is the difference between epithelial cells and connective tissues in terms of organ structure?
In most organs, epithelial cells form the parenchyma, or the functional parts, of the organ. In most organs, connective tissue forms the stroma , or support structure, by secreting materials to form an ECM. Thus bones, cartilage, tendons, ligaments, adipose tissue, and blood are all examples of connective tissues. The connective tissue secretes materials to form an ECM.
How is beta-oxidation of polyunsaturated fatty acids different from that of saturated fatty acids.
In polyunsaturated fatty acids, 2,4-dienoyl-CoA reductase is needed to perform reduction that converts two conjugated double bonds to just one double bond at the 3,4 position, where it will then undergo the same rearrangement as monounsaturated fatty acids: Enoyl-CoA isomerase rearranges cis double bonds at the 3,4 position to trans double bonds at the 2,3 position once enough acetyl-CoA has been liberated to isolate the double bond within the first three carbons.
What is the difference between prokaryotes and eukaryotes in terms of translation?
In prokaryotes, the ribosomes start translating before the mRNA is complete in eukaryotes, however, transcription and translation occur at separate times and in separate locations within the cell (transcription in the nucleus and translation in the cytoplasm).
Why do we have to use modified standard state in biological systems?
In standard state concentration = 1 M, pressure = 1 atm, and temperature = 25 C (298 K). Biochemical analysis works well under all standard conditions except one: pH. A 1 M concentration of protons would correspond to a pH of 0, which is far too acidic for most biochemical reactions. Therefore in the modified standard state [H+] = 10^-7 M and the pH is 7. With this additional condition, ∆G° is given the special symbol ∆G°', indicating that it is standardized to the neutral buffers used in biochemistry. Note that if the concentrations of the other reactants and products differ from 1 M, these must still be adjusted for in the equation ∆G=∆G° + RTln(Q) [where Q is the reaction quotient]
What is a collection of cell bodies celled in the CNS? In the PNS?
In the CNS it is called a nucleus. In the PNS t is called a ganglion.
Describe natural killer cells
In the arms race between the human immune system and pathogens, some pathogens have found ways to avoid certain defenses. For example, some viruses cause downregulation of MHC molecules, making it harder for T-cells to recognize the presence of an infection. Natural Killer (NK) cells, a type of nonspecific lymphocyte, are able to detect the downregulation of MHC and induce apoptosis in these virally infected cells. Note: Cancer cells may also downregulate MHC production, so NK cells also offer protection from the growth of cancer as well. Thus, NK cells are activated by cells that do not present MHC (such as virally infected cells and cancer cells)
What's the difference between NADH and NADPH?
In the cell, NAD+ acts as a high energy electron acceptor from a number of biochemical reactions. It thus can be thought of as a potent oxidizing agent because it helps another molecule be oxidized. The NADH produced from the reduction of NAD+ can then feed into the electron transport chain to indirectly produce ATP. Thus NAD+ is an energy carrier. Conversely, NADPH primarily acts as an electron donor in a number of biochemical reactions. It thus can be thought of as a potent reducing agent because it helps other molecules be reduced.
Describe how fatty acid oxidation can lead to acetyl-CoA formation
In the cytosol, a process called activation causes a thioester bond to form between carboxyl groups of fatty acids and CoA-SH. Because this activated fatty acyl-CoA cannot cross the inner mitochondrial membrane, the fatty acyl group is transferred to carnitine via a transesterification reaction. Carnitine is a molecule that can cross the inner membrane with a fatty acyl group in tow, Once acyl-carnitine crosses the inner membrane; it transfers the fatty acyl group to a mitochondrial CoA-SH via another transesterification reaction. In other words, carnitine's function is merely to carry the acyl group from a cytosolic CoA-SH to a mitochondrial CoA-SH. Once acyl-CoA is formed in the matrix, beta-oxidation can occur, which removes two-carbon fragments from the carboxyl end forming acetyl-CoA
Describe the lysogenic cycle
In the even that a virus does not lyse the bacterium, it may integrate into the host genome as a provirus or prophage, initiating the lysogenic cycle. In this case, the virus will be replicated as the bacterium reproduces because it is now a part of the host's genome. Note: Although the virus may remain integrated into the host genome indefinitely, environmental factors (radiation, light, or chemicals) may cause th eprovirus to leave the genome and revert to a lytic cycle. The provirus may extract bacterial genes as it leaves the genome, which allows transduction of gene from one bacterium to another.
Where does fatty acid synthesis occur?
In the liver. Then its products are transported to adipose tissue for storage-the primary end product of fatty acid synthesis is palmitic acid (palmitate) Note: adipose tissue can also synthesize smaller quantities of fatty acids.
Describe the numbering system of DNA coding strands
In the vicinity of a gene, a numbering system is used to identify the location of important bases in the DNA strand. The first base transcribed from DNA to RNA is defined as the +1 base of that gene region. Bases to the left of this start point (upstream, or toward the 5' end) are given negative numbers: -1, -2, -3, and so on. Bases to the right (downstream, or toward the 3' end) are denoted with positive numbers: +2, +3, +4, and so on. Thus, no nucleotide in the gene is numbered 0. Note: The TATA box, where RNA polymerase II bonds, usually falls around -25.
Describe ion exchange chromatography
In this method of chromatography, the beads in the column are coated with charged substances so they attract or bind compounds that have an opposite charge. After all other compounds have moved through the column, a salt gradient is used to elute the charged molecules that have stuck to the bottom.
Describe noncompetitive inhibition
In this process, the inhibitor binds to an allosteric site instead of the active site. Allosteric sites are non-catalytic regions of the enzyme that bind regulators. Because the molecules do not bind at the same site, inhibition is considered non-competitive and cannot be overcome by adding more substrate. Noncompetitive inhibitors bind equally well to the E and ES-complex, unlike mixed inhibitors. Thus, a noncompetitive inhibitor decreases Vmax, it will not, however, affect Km because any enzymes that are active maintain the same affinity for their substrate.
How is beta-oxidation of monounsaturated fatty acids different from that of saturated fatty acids.
In unsaturated fatty acids, two additional enzymes are necessary because double bonds can disturb the stereochemistry needed for oxidative enzymes to act on the fatty acid. To function, these enzymes can have at most one double bond in their active site; this bond must be located between carbons 2 and 3. Enoyl-CoA isomerase rearranges cis double bonds at the 3,4 position to trans double bonds at the 2,3 position once enough acetyl-CoA has been liberated to isolate the double bond within the first three carbons. In monosaturated fatty acids, this single step permits beta-oxidation to proceed.
Describe inclusive fitness
Inclusive fitness is a measure of an organism's success in the population, based on the number of offspring, success in supporting offspring, and the ability of the offspring to then support others. Inclusive fitness promotes the idea that altruistic behavior can improve fitness and success of a species as a whole. Unlike Darwin's fitness, inclusive fitness go beyond the individual level
Describe incomplete dominance
Incomplete dominance occurs when a heterozygote expresses a phenotype that is intermediate between the two homozygous genotypes. A classic example of incomplete dominance is the mating of certain flowers, in which a red flower crossed with a white flower results in pink flowers,
What are inducers?
Inducers are often growth factors, which are peptides, that promote differentiation and mitosis in certain tissues Reciprocal induction is a special case in which two tissues both induce further differentiation on each other
Describe induction
Induction is the ability of one group of cells to influence the fate of nearby cells. This process is mediated by chemical substances called inducers which diffuses from the organizing cells to the responsive cells. These chemicals are responsible for processes such as the guidance of neuronal axons. Induction also ensures the proximity of different cell types that work together within an organ.
Why can a provirus/prophage be beneficial to a bacterium?
Infection with one strain of phage generally makes the bacterium less susceptible to superinfection (simultaneous infection)
What are the stages of the virus life cycle?
Infection, translation and progeny assembly, progeny release, and lytic and lysogenic cycles
Describe inhalation
Inhalation is an active process. We use our diaphragm as well as the external intercostal muscles to expand the thoracic cavity. As the diaphragm flattens and the chest wall expands outward, the intrathoracic volume increases. This leads to a decrease in intrapleural pressure. Now we have low pressure in the intrapleural space. The gas in the lungs is initially at atm pressure, which is now higher than the pressure in the intrapleural space. The lungs will therefore expand into the intrapleural space and the pressure in the lungs will drop. Air will then be sucked in from a higher-pressure environment -- the outside world. This mechanism is referred to as negative-pressure breathing because the driving force is the lower (relatively negative) pressure in the intrapleural space compared with the lungs.
What's the difference between innate immunity and adaptive immunity?
Innate immunity refers to the responses cells can carry out without learning; for this reason, it is also known as the nonspecific immune response. Conversely, adaptive immunity is developed as immune cells learn to recognize and respond to particular antigens, and is often aptly referred to as the specific immune response.
What promotes beta-oxidation? What inhibits it?
Insulin indirectly inhibits beta-oxidation while glucagon stimulates this process
Describe insulin
Insulin is secreted from beta-cells of the islet of Langerhans. It is antagonistic to glucagon and is therefore secreted when blood glucose levels are high. Insulin induces muscle and liver cells to take up glucose and store it as glycogen for later use. IN addition, because it is active when glucose levels are high, insulin stimulates anabolic processes such as fat and protein synthesis.
What is the relationship between PFK-1 and PFK-2?
Insulins stimulates and glucagon inhibits PFK-1 in hepatocytes by an indirect mechanism involving PFK-2 and fructose 2,6-bisphosphate. Insulin activates phosphofructokinase-2 (PFK-2), which converts a tiny amount of fructose 6-phosphate to fructose 2,6-bisphosphate. F2,6BP activates PFK-1. On the other hand, glucagon inhibits PFK-2, lowering F2,6-BP and thereby inhibiting PFK-1. PFK-2 is found mostly in the liver. By activating PF-1 it allows the cells to override the inhibition caused by ATP so that glycolysis can continue, even when the cell is energetically satisfied. THe metabolites of glycolysis can thus be fed into the production of glycogen, fatty acids, and other storage molecules rather than just be burned to produce ATP.
Name examples of intermediate filaments
Intermediate filaments are involved in cell-cell adhesion and maintenance of the integrity of the cytoskeleton. Examples include: keratin, desmin, vimentin, or lamins
Describe interneurons
Interneurons are located predominantly in the brain and the spinal cord and are often linked to reflexive behavior.
Draw Isoleucine
Iso; I * one carbon lives alone
Describe pancreatic lipase
It breaks down fats into free fatty acids and glycerol
How does stomach acid provide immunology?
It can act as an antimicrobial
What is cool about hydrogen peroxide?
It can be an oxidizing or reducing agent
Describe a gram positive cell wall
It consists of a thick layer of peptidoglycan and lipoteichoic acid. In addition to its structural and barrier functions, the cell wall may also aid a bacterial pathogen by providing protection from a host organism's immune system. A prokaryote with this type of wall will stain purple given a crystal violet stain and a counterstain called safranin due to the fact that it does not have an outer-membrane: "Can purple enter? Positive."
What helps the eukaryotic cell hold its structure and maintain its shape
Its cytoskeleton. It has three components: microfilaments, microtubules, and intermediate filaments
What are the units for entropy?
J/K
What conditions and tissues favor ketogenesis? Ketolysis?
Ketogenesis is favored by a prolonged fast and occurs in the liver. It is stimulated by increasing concentrations of acetyl-CoA. Ketolysis is also favored during a prolonged fast but is stimulated by a low-energy state in muscle and brain tissues and does not occur in the liver.
Describe ketogenesis
Ketogenesis occurs in the mitochondria of liver cells when excess acetyl-CoA accumulates in the fasting state. HMG-CoA synthase forms HMG-CoA and HMG-CoA lyase breaks down HMG-CoA into acetoacetate which can subsequently be reduced to 3-hydroxybutyrate (a ketone body type). Acetone is a minor side product that is formed but will not be used as energy for tissues.
Describe ketone bodies
Ketone bodies are essentially transportable forms of acetyl-CoA. They are produced by the liver and used by other tissues during prolonged starvation.
Why is it that Ketose's can give positive Tollens' and Benedict's tests?
Ketose sugars are also reducing sugars. Although ketones cannot be oxidized directly to carboxylic acids, they can tautomerize to form aldoses under basic conditions, via keto-enol shifts. Then in their aldose form they can react with the before mentioned reagents to form the carboxylic acid.
What is Km?
Km is the substrate concentration at which half of the enzyme binding sites are full. Under certain conditions, it is a measure of the affinity of the enzyme for the substrate. It is also the value at half Vmax. Thus, when comparing two enzymes, the one with the higher Km has the lower affinity for its substrate because it requires a higher concentration to be half saturated. Note: the Km value is an intrinsic property of the enzyme-substrate system and cannot be changed by changing the [substrate] or [enzyme].
What configuration are al eukaryotic chiral amino acids found in?
L-configuration
Describe LCAT and CETP
LCAT (lecithin-cholesterol acyltransferase) is an enzyme found in the bloodstream that is activated by HDL apoproteins. LCAT adds a fatty acid to cholesterol, which produces soluble cholesteryl esters such as those in HDL. HDL cholesteryl esters can be distributed to other lipoproteins like IDL, which becomes LDL by acquiring these cholesteryl esters. The cholesteryl ester transfer protein (CETP) facilitates this transfer process
What are the functions of LDL
LDL delivers cholesterol into cells
What can happen if a person lacks a particular disaccharidase?
Lack of a particular disaccharidase causes an inability to break down the corresponding disaccharide. The bacteria in the intestines are able to hydrolyze that disaccharide , producing methane gas as a byproduct. In addition, undigested disaccharides can have an osmotic effect, pulling water into the stool and causing diarrhea. This is why people who are lactose intolerant have symptoms of bloating, flatulence, and possibly diarrhea after ingesting dairy products.
Describe lactate dehydrogenase
Lactate dehydrogenase is the rate-limiting enzyme in fermentation. It oxidizes NADH to NAD+, replenishing the oxidized coenzyme for G3P dehydrogenase. Without mitochondria and oxygen, glycolysis would stop when all the available NAD+ had been reduced to NADH. By reducing pyruvate to lactate and oxidizing NADH to NAD+, lactate dehydrogenase prevents this potential problem, from developing.
How does lactate enter gluconeogenesis?
Lactate is directly converted to Pyruvate by the enzyme Lactate Dehydrogenase (LDH)
Describe leptin
Leptin is a hormone secreted by fat cells that decreases appetite by suppressing orexin production.
Draw Leucine
Leu; L *it's a Long valine (add one more carbon)
What is the parietal pleura?
Lines the inside of the thoracic cavity, a small amount of fluid is between the pleurae in the intrapleural space. This fluid helps lubricate the two pleural surfaces and reduces friction during breathing
Describe lipid digestion and the role of bile
Lipid digestion begins in the mouth. It is carried out by lingual lipase released by Ebner's glands on the tongue. It will turn TAGs into free fatty acids and DAGs--25-30% Digestion of the lipids continues in the stomach via gastric lipase released from chief cells. They will turn TAGs into FFA and DAGs contributing to the 25-30% This means that by the time we get to the duodenum, we have some monoglycerides, free fatty acids, and cholesterol but 70-75% of the lipids still need to be digested: As this fatty chyme enters the small intsetine, CCK will be released and it will trigger the release of bile and pancreatic enzymes. The bile will surround the fat droplets and emulsify the. Then digestion of the lipids will be carried out by pancreatic lipase and colipase: precolipase is converted into colipase (by trypsin activated by enterokinase) and it will open up a "door" into the bile surrounding the lipids so that the pancreatic lipase can get in and act -- turning the remainder TAGs into FFA and 2MGs. Cholesterol esterase plays a role as well. *Bile is amphipathic so it forms a micelle with the hydrophobic ends facing lipid and the hydrophilic ends facing the water so that it can taxi the lipid across the unstirred water layer to the enterocytes. Once there, the lipids inside the taxi are able to diffuse into the lipid bilayer and the bile remains behind.
Describe the digestion of lipids
Lipid digestion is minimal in the mouth and stomach: lipids are transported to the small intestine essentially intact. Upon entry into the duodenum, emulsification occurs, which is the mixing of two normally immiscible liquids (in this case, fat and water). Formation of an emulsion increases the surface area of the lipid, which permits greater enzymatic interaction and processing. Emulsification is aided by bile, which contains bile salts, pigments, and cholesterol; bile is secreted by the liver and stored in the gall bladder. Finally, the pancreas secretes pancreatic lipase, colipase, and cholesterol esterase into the small intestine; together, these enzymes hydrolyze the lipid components to 2-monoacylglycerol, free fatty acids, and cholesterol.
Describe lipid rafts
Lipid rafts are aggregates of specific lipids in the membrane that function as attachment points for other biomolecules and play role sin signaling. Note: These are cholesterol rich domains
What's the difference between lipid-soluble vitamins and water-soluble vitamins?
Lipid-soluble vitamins can accumulate in stored fat, whereas excess water-soluble vitamins are excreted through the urine.
What plays the largest role in the stability of secondary structures of proteins?
Local hydrogen bonds
Describe the gastric glands of the stomach
Located in the fundus and the body, the gastric glands respond to signals from the vagus nerve of the parasympathetic nervous system, which is activated by the brain in response to the sight, taste, and smell of food. Gastric glands have three different cell types: mucous cells, chief cells, and parietal cells.
What does low blood pressure do to the glomerular filtration rate?
Lower it; allowing for more reabsorption of contents
Describe MHC-II molecules
MHC class II molecules are mainly displayed by professional antigen-presenting cells like macrophages. Remember that these phagocytic cells pick up pathogens from the environment, process them, and then present them on MHC-II. An antigen is a substance (usually a pathogenic protein) that can be targeted by an antibody. While antibody production is the domain of the adaptive immune system, it is important to understand that cells of the innate immune system also present antigens. In this case, because these antigens originated outside the cell, the MHC-II pathway is often called the exogenous pathway. The presentation of an antigen by an immune cell may result in the activation of both the innate and adaptive immune systems. Note: Professional antigen-presenting cells include macrophages, dendritic cells in the skin, some B-cells, and certain activated epithelial cells
Describe macrophages
Macrophages, a type of agranulocyte, reside within tissues. These cells derive from blood-borne monocytes and can become a resident population with a tissue (becoming a permanent, rather than transient, cell group in the tissue).When a bacterial invader enters a tissue, the macrophages become activated. The activated macrophage then does three things: First, it phagocytoses the invader through endocytosis. Then, it digests the invader using enzymes. Finally, it presents little pieces of the invader (mostly peptides) to other cells using a protein called major histocompatibility complex (MHC). MHC binds to a pathogenic peptide (also called an antigen) and carries it to the cell surface, where it can be recognized by cells of the adaptive immune system/ In addition, macrophages release cytokines, chemical substances that simulate inflammation and recruit additional immune cells to the area.
What can happen if a mother lacks folic acid?
Maternal folic acid deficiency may prevent complete closure of the neural tube resulting in spina bifida or anencephaly.
Describe the splicing process of mRNA
Maturation of the hnRNA includes splicing of the transcript to removed introns and ligate exons together. Splicing is accomplished by the spliceosome. In the spliceosome, small nuclear RNA (snRNA) molecules couple with proteins known as small nuclear ribonucleoproteins (snRNPs). The snRNP/snRNA complex recognized both the 5' and 3' splice sites of the introns. These noncoding sequences are excised in the form of a lariat (lasso-shaped structure) and then degraded.
Describe the structure of spermatazoa
Mature sperm are very compact. They consist of a head (containing the genetic material), a midpiece (which generates ATP from fructose), and a flagellum (for motility). *The midpiece is filled with mitochondria which generate the energy for swimming. --this will disintegrate within the egg following penetration of the egg *Each sperm head is coated by a cap called an acrosome. This structure is derived from the golgi aparatus and is neessary to penetrate the ovum.
When does a secondary oocyte enter meiosis II?
Meiosis II is triggered when a sperm cell penetrates the corona radiata and the zona pellucida with the help of its acrosomal enzymes. The secondary oocyte then undergoes meiotic division to split into a mature ovum and another polar body which will be eventually broken down.
Describe meiosis
Meiosis occurs in gametocytes (germ cells) and results in up to four NON-IDENTICAL sex cells (gametes). Unlike mitosis that consists of one round each of replication and division, meiosis consists of one round of replication followed by two rounds of division. This consists of: Meiosis I which results in homologous chromosomes being separated generating haploid daughter cells (known as educational division). Meiosis II which is similar to mitosis in that it results in the separation of sister chromatids without a change in ploidy (known as equatorial division)
Which components of membrane lipids contribute to their structural role in membranes? Which components contribute to function?
Membrane lipids are amphipathic they have hydrophilic heads and hydrophobic tails, allowing for the formation of bilayers in aqueous solution. The fatty acid tails form the bulk of the phospholipid bilayer and play a predominantly structural role. ON the other hand, the functional differences between membrane lipids are determined by the polar head group, due to its constant exposure to the exterior environment of the phospholipid bilayer (remember, this can be either the inside or the outside of the cell). The degree of unsaturation of fatty acid tails can also play a small role in function.
With which phase of meiosis does each of Mendel's laws most closely correlate? Mendel's first law. Mendel's Second law.
Mendel's first law (of segregation) most aligns with anaphase I of meiosis. Mendel's second law (of independent assortment) most aligns with prophase I of meiosis
Describe mRNA
Messenger RNA (mRNA) carries the information specifying the amino acid sequence of the protein to the ribosome. mRNA is transcribed from the template DNA strand by RNA polymerase enzymes in the nucleus of cells. Then mRNA may undergo a host of posttranscriptional modifications prior to its release from the nucleus. mRNA is the only type of RNA that contains information that is translated into proteins. Note: active mRNA has a very short lifespan -- in order for protein synthesis to continue, more mRNA must be transcribed.
Draw and describe methionine
Met; M
What are myocytes?
Muscle cells. Each myocyte contains many myofibrils arranged in parallel and can also be called a muscle fiber. The nuclei of which there are many are usually found at the periphery of the cell. Finally, many myocytes in parallel form a muscle.
What are transgenic mice?
Mice that are altered at their germ line by introducing a cloned gene into fertilized ova or into embryonic stem cells. The cloned gene that is introduced is referred to as a transgene. If the transgene is a disease-producing allele, the transgenic mice can be used to study the disease process from early embryonic development through adulthood. A similar approach can be used to produce knockout mice, in which a gene has been intentionally deleted (knocked out).
Describe microfilaments
Microfilaments are made up of solid polymerized actin. Actin can use ATP to generate force for movement by interacting with myosin, such as in muscle contraction. Microfilaments also play a role in cytokinesis, or the division of materials between daughter cells.
Describe microtubules
Microtubules are hollow polymers of tubulin proteins. Microtubules originate from centrosomes and radiate through the cell providing the primary pathways along which motor proteins like kinesis and dynein carry vesicles.
When does milk ejection occur?
Milk ejection occurs when the newborn infant latches onto the breast. Nipple simulation causes activation of the hypothalamus, resulting in two different reactions: First: oxytocin is released from the posterior pituitary, resulting in contraction of the smooth muscle of the breast and ejection of milk through the nipple. Second: the hypothalamus stops releasing dopamine onto the anterior pituitary, which allows prolactin release, causing production of milk and regulation of the milk supply.
Describe mineralcorticoids
Mineralocorticoids are used in salt and water homeostasis; their most profound effects are on the kidneys. The most noteworthy mineralocorticoid is aldosterone, which increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron. Water follows the sodium cations into the bloodstream increasing blood volume and pressure. Since water and sodium ions flow together, plasma osmolarity remains unchanged; this is in contrast to ADH, which only increases water reabsorption (decreasing plasma osmolarity). Aldosterone also decreases the reabsorption of potassium and hydrogen ions in these same segments of nephron, promoting their excretion in the urine.
What organelles can cause apoptosis of a cell?
Mitochondria are capable of kick-starting apoptosis by the release of enzymes from the ETC. Lysosomes can cause apoptosis via autolysis.
What about mitochondria division supports the endosymbiosis theory?
Mitochondria can divide independently of the nucleus via binary fission, like prokaryotes.
Describe the membranes of the mitochondria
Mitochondria contain two membranes which differ from the cell membrane: the inner and outer mitochondrial membranes Outer mitochondrial membrane: The outer mitochondrial membrane is highly permeable due to many large pores that allow the passage of ions and small proteins. The outer membrane completely surrounds the inner mitochondrial membrane, with the presence of a small intermembrane space in between the two layers. Inner Mitochondrial Membrane: The inner mitochondrial membrane has a much ore restricted permeability compared to the outer mitochondrial membrane. Structurally, the inner mitochondrial membrane contains numerous infoldings called cristae, which increase the available surface area for the integral proteins associated with the membrane. These proteins are involved in the ETC and ATP synthesis/ The inner membrane also encloses the mitochondrial matric, where the citric acid cycle produces high-energy electron carries used in the ETC. The inner mitochondrial membrane contains a very high level of cardiolipin and does not contain cholesterol.
Describe mixed inhibition
Mixed inhibition results when an inhibitor can bind to either the E or the ES-complex but has a different affinity for each (if the inhibitor had the same affinity for both it'd be noncompetitive inhibition). Mixed inhibition does not bind to a competitive site but to an allosteric site. Mixed inhibition alters Km depending on the preferences of the inhibitor for the E vs Es-complex: *If the inhibitor preferably binds to the enzyme, it increases Km (lowers affinity) because the substrate can't bind *If the inhibitor binds to the ES complex, it decreases Km (increases affinity) because it forces the substrate to stay bound and prevents product formation
Describe monocytes
Monocytes phagocytize foreign matter such are bacteria. Most organs of the body contain a collection of these phagocytotic cells once they leave the bloodstream and enter an organ, monocytes are renamed macrophages. Each organ's macrophage population may have a specific name as well. In the central nervous system, for example, they are called microglia; in the skin, they are called Langerhans cells; in bone, they care called osteoclasts.
How do we classify monozygotic twins?
Monozygotic twins can be classified by the number of structures they share *Monocorionic/monoamniotic twins share the same amnion and chorion *Monochorionic/diamniotic twins have their own amnion but share the same chorion *Dichorionic/diamniotic twins each have their own amnions and chorions
Where do cells get cholesterol?
Most cells derive their cholesterol from LDL or HDL, but some cholesterol may be synthesized de novo. De novo synthesis of cholesterol occurs in the liver and is driven by acetyl-CoA and ATP.
What is bone formed from?
Most of the bones of the body are created by the hardening of cartilage into bone. This process is known as endochondral ossification and is responsible for the formation of most of the long bones of the body. Bones may also be formed through intramembranous ossification, in which undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into, and replaced by bone. This occurs in bones of the skull.
What is the pathway of air into the lungs?
Mouth/nose, pharynx, larynx, trachea, bronchi, bronchioles, alveoli
Describe the structure of movable joints
Movable joints are strengthened by ligaments, which are pieces of fibrous tissue that connect bones to one another, and consist of a synovial capsule, which encloses the actual joint cavity (articular cavity). A layer of soft tissue called the synovium secretes synovial fluid, which lubricates the movement of structures in the joint space. The articular cartilage contributes to the joint by coating the articular surfaces of the bones so that the impact is restricted to the lubricated joint cartilage, rather than to the bones.
Describe the activity of the catecholamines epinephrine and norepinephrine
Much like the sympathetic components of the ANS, the hormones released from the adrenal medulla have diverse system-wide effects, all centered on the fight-or-flight response: *Epinephrine can increase the breakdown of glycogen to glucose (glycogenolysis) in both liver and muscle, as well as increase the basal metabolic rate. *Both epinephrine and norepinephrine will increase heart rate, dilate the bronchi, and shunt blood flow to the systems that would be used in a sympathetic response. That is, there is vasodilation of blood vessels leading to increased blood flow to the skeletal muscle, heart, lungs, and brain. Concurrently, vasoconstriction decreases blood flow to the gut, kidneys, and skin.
What is the function of mucous cells of the stomach?
Mucous cells produce the bicarbonate rich mucus that protects the muscular wall from the harshly acidic (pH=2) and proteolytic environment of the stomach.
Describe the activation style of muscles
Muscle cells, like neurons, exhibit an all or nothing response; either they respond completely to a stimulus or not at all. For muscle cells to respond, stimuli must reach a threshold value. The strength of a response from one muscle cell cannot be changed because the only options are all or nothing. Therefore, nerves control overall force by the number of motor units they recruit to respond. Maximal response occurs when all fibers within a muscle are stimulated to contract simultaneously.
What does muscle do with excess glucose? What about adipose tissue?
Muscle stores excess glucose as glycogen, and adipose tissue requires glucose to form dihydroxyacetone phosphate (DHAP), which is converted to glycerol phosphate to store incoming fatty acids as triacylglycerols.
What creates myelin?
Myelin is produced by oligodendrocytes in the CNS and Schwann cells in the PNS
It what direction is protein synthesized?
N-terminus to C-terminus
Describe the concept of NADH shuttles
NADH formed through glycolysis cannot directly cross into the mitochondiral matrix. Bexause it cannot contribute is electrons to the transport chain directly, i mus tfind alternate emans of transportation referred to as shuttle mechanisms. A shuttle mechanism transfers the high-energy electros of NADH to a carrier that can cross the inner mitochondrial membrane. Depending on which of the twoshuttle mechanisms NADH participates in, either 1.5 or 2.5 ATP will end up beinf produced. thats why the net yiled of ATP per glucose is a range of 30-32.
What are the main functions of NADPH?
NAPH is involved in lipid and cholesterol biosynthesis, bactericidal bleach formation in certain white blood cells (immune system), and maintenance of glutathione stores tp protect against reactive oxygen species (prevents oxidative damage).
Describe stabilizing natural selection
Natural selection that favors intermediate variants by acting against extreme phenotypes Stabilizing selection keeps phenotypes with a specific range by selecting against extremes. For example, human birth weight is maintained within a narrow band by stabilizing selection.
Describe directional natural selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
cathode
Negative electrode that attracts positive charges
Describe negative sense viruses
Negative sense RNA viruses have strands that act as a template for a complementary strand which can then be used for protein synthesis--this involves single stranded RNA. Negative-sense RNA viruses MUST carry an RNA replicase in the virion to ensure the complementary strand is synthesized- this happens in the cytosol. "Is synthesis direct? Negative."
Describe the adrenal medulla
Nestled inside the adrenal cortex is the adrenal medulla. A derivative of the nervous system, this organ is responsible for the production of the sympathetic hormones epinephrine and norepinephrine. These specialized nerve cells in the medulla are capable of secreting these compounds directly into the bloodstream. Both epinephrine and norepinephrine are amino-acid derivative hormones that belong to a class of molecules known as catecholamines.
Describe neuralation
Neuralation is the development of the nervous syste,. This occurs once the three germ layers are formed.
Does the increased intensity of a stimulus result in an increased potential difference of an action potential?
No, action potentials are all or nothing. So it will just result in increased frequency of AP
Can spirometry measure total lung capacity?
No, because it can't measure residual volume.
Does the amount of DNA in an organism ever change?
No, it is always constant. During replication, the amount of DNA doubles. But other than that, the amount of DNA in a cell, even one infected by a persistent virus, remains constant.
Is hemoglobin normally found in blood plasma?
No, it is found in red blood cells. Presence of hemoglobin in plasma suggests hemolysis
Is natural selection the same thing as evolution?
No, it is simply a mechanism for evolution. Natural selection works on an individual level --populations evolve, not individuals
Can men give sex linked traits to their sons?
No, the X always goes to the daughters, the men give their Y's to the sons
Do prokaryotes have a nucleus?
No, they have a nucleoid
What is non disjunction?
Non-disjunction refers to the incorrect segregation of homologous chromosomes during anaphase I, or of sister chromatids during anaphase II. In either case, one daughter cell ends up with two copies of related genetic material while the other receives zero. Note: this is the cause of trisomy 21 -- down syndrome
Described the activation of B-cells
Not all B-cells that are generated actively or constantly produce antibodies. Antibody production is an energetically expensive process, and there is no reason to expend energy to produce antibodies that are not needed. Instead, naive B-cells (those that have not yet been exposed to an antigen) wait in the lymph nodes for their particular antigen to come along. Upon exposure to the correct antigen, a B-cell will proliferate and produce two types of daughter cells: plasma cells produce large amounts of antibodies, whereas memory B-cells stay in the lymph node, awaiting reexposure to the same antigen. This initial activation takes approximately seven to ten days and is known ad the primary response. The plasma cells will eventually die, but the memory cells may last the lifetime of the organism. If the same microbe is ever encountered again, the memory cells jump into action and produce the antibodies specific to that pathogen. This immune response, called the secondary response, will be more rapid and robust. The development of these lasting memory cells is the basis of the efficacy of vaccination.
What are nucleosides?
Nucleosides are composed of a five-carbon sugar (pentose) bonded to a nitrogenous base and are formed by covalently linking the base to C-1' of the sugar. Note that the carbon atoms in the sugar are labeled with a prime symbol to distinguish them from the carbon atoms in the nitrogenous base.
What is the key structural difference in the type of lesions corrected by nucleotide excision repair vs those corrected by base excision repair?
Nucleotide excision repair corrects lesions that are large enough to distort the double helix; base excision repair corrects lesions that are small enough not to distort the double helix.
What are nucleotides?
Nucleotides are formed when one or more phosphate groups are attached to C-5' of a nucleoside. Often these molecules are named according to the number of phosphates present. Adenosine di- and triphosphate (ADP and ATP ), for example, gain their names from the number of phosphate groups attached to the nucleotide adenosine. These are high-energy compounds because of the energy associated with the repulsion between closely associated negative charges on the phosphate groups.
How are nucleotides bound together in DNA?
Nucleotides are linked to one another by phosphodiester bonds between the sugar base of one nucleotide and the phosphate group of the adjacent nucleotide in a way way that the 5' end bears a phosphate, and the 3' end a hydroxyl group
Describe the process of transcription
Once RNA polymerase is on the promoter region of the template strand, RNA polymerase travels along with the template strange in the 3' -> 5' direction, which allows for the construction of transcribed mRNA in the 5' -> 3' direction. Unlike DNA polymerase, RNA polymerase does not proofread its work so the synthesized transcript will not be edited. Note: The coding strand (or sense strand) of DNA is not used as a template during transcription. Because the coding strand is also complementary to the template strand, it is identical to the mRNA transcript except that all the thymine nucleotides in DNA have been replaced with uracil in the RNA molecule
Describe gastrulation
Once the cell mass implants, it can begin further developmental processes such as gastrulation the generation of three distinct cell layers. Gastrulation begins with a small invagination in the blastula. Cells continue moving toward the invagination, resulting in elimination of the blastocoel. The two sides (membranes) eventually merge creating a tube through the middle. The result of this is the gastrula.
Describe IDL
Once triacylglycerol is removed from VLDL, the resulting particle is referred to as either a VLDL remnant or IDL. Some IDL is reabsorbed by the liver by apolipoproteins on its exterior, and some is further processed in the bloodstream. For example, some IDL picks up cholesteryl esters from HDL to become LDL. IDL thus exists as a transition particle between triacylglycerol transport(associated with chylomicrons and VLDL) and cholesterol transport (associated with LDL and HDL).
Describe the involvement of cancer with the cell cycle
One of the most common mutations found in cancer is a mutation of the gene that produces p53, called TP53. When this gene is mutated, the cell cycle is not stopped to repair damaged DNA. This allows mutations to accumulate. Often, cells can undergo rapid cell division, creating tumors
What are the layers of an oocyte?
Oocytes are surrounded by two layers: *the zona pellucida which surrounds the oocyte itself and is an acellular mixture of glycoproteins that protect the oocyte and contain compounds necessary fr sperm cell binding. *the corona radiata (radiating corona- on the outside) which lies outside the zona pellucida and is a layer of cells that adhered to the oocyte during ovulation
What enzymes regulate pyruvate dehydrogenase?
PDH kinase and PDH phosphatase
In bacterial sepsis (overwhelming bloodstream infection), a number of capillary beds throughout the body open simultaneously. What effect would this have on the blood pressure? Besides the risk of infection, why might sepsis be dangerous for the heart?
Opening up more capillary beds (which are in parallel) will decreases overall resistance of the cricuit. The cardiac output will therefore increase in an attempt to maintain constant blood pressure. This is a risk to the heart because the increased demand on the heart can eventually tire it, leading to a heart attack or a precipitous drop in blood pressure.
Describe osmosis
Osmosis is a specific type of simple diffusion that concerns water
Describe osmotic pressure. What is the formula for it
Osmotic pressure, a colligative property, is the pressure applied to a pure solvent to prevent osmosis and is used to express the concentration of the solution. It is often better conceptualized as a "sucking" pressure in which a solution is drawing water in, proportional to its concentration. The formula is: π= iMRT *where M is the molarity of the solution, R si the ideal gas constant, T is the absolute temperature (in kelvins), and i is the van't Hoff factor (which is simply the number of particles obtained from the molecule when in solution). For example, glucose remains one intact molecule so iglucose= 1 but iNaCl would be 2
What is another name for oncotic pressure?
Osmotic pressure; it is caused by proteins
What stimulates ovulation?
Ovulation is simulated by a sudden surge in LH. This surge is triggered when estrogen levels reach a threshold and switch from negative to positive effects.
Describe oxidative phosphorylation
Oxidative phosphorylation is the generation of ATP via the ETC. This involves the pumping of protons from the mitochondrial matrix to the intermembrane space, this establishes the proton motive force.
Describe oxytocin
Oxytocin is secreted during childbirth and allows for coordinated contraction of uterine smooth muscle. Its secretion may also be simulated by suckling, as it promotes milk ejection through contraction of smooth muscle in the breast. Finally oxytocin may be involved in bonding behavior. Oxytocin is unusual in that it has a positive feedback loop the release of oxytocin promotes uterine contraction, which promotes more oxytocin release, which promotes stronger uterine contractions, and so on. Positive feedback loops can usually be identified by a spiraling forward scheme and usually have a definitive endpoint --in this case delivery.
Describe PEPCK
PEPCK in the cytoplasm is induced by glucagon and cortisol, which generally act to raise blood sugar levels. It converts OAA to PEP in a reaction that requires GTP. PEP continues in the pathway to fructose 1,6- bisphosphate. Thus the combination of pyruvate carboxylase and PEPCK are used to circumvent the action of pyruvate kinase by converting pyruvate back to PEP
Describe phosphofructokinase-1
PFK-1 is the rate limiting enzyme and main control point in glycolysis. In this reaction, fructose 6-phosphate is phosphorylated to fructose 1,6-bisphosphate (F16BP) using ATP. PFK-1 is inhibited by ATP and citrate, and activated by AMP. This makes sense because the cell should turn off glycolysis when it has sufficient energy (high ATP) and turn on glycolysis when it needs energy (high AMP) --citrate is an intermediate of the citric acid cycle, so high levels of citrate also imply that the cell his producing sufficient energy.
what is the only fatty acid that humans can synthesize?
Palmitic acid (16:0)
Describe parallel evolution
Parallel evolution refers to the process whereby related species evolve in similar ways for a long period of time in response to analogous environmental selection pressures.
What does parathyroid hormone do to bone?
Parathyroid hormone, a peptide hormone released by the parathyroid glands in response to low blood calcium, promotes resorption of bone, increasing the concentration f calcium and phosphate in the blood.
Describe basophils
Part of the innate immune system, basophils contain large purple granules and are involved in allergic responses. They are the least populous leukocyte in the bloodstream under normal conditions. Mast cells are closely related to basophils, but have smaller granules and exist in the tissues, mucosa, and epithelium. Both basophils and mast cells release large amounts of histamine in response to allergens, leading to inflammatory responses.
Describe eosinophils
Part of the innate immune system, eosinophils contain red-orange granules and are primarily involves in allergic reactions and invasive parasitic infections. Upon activation, eosinophils release large amounts of histamine, an inflammatory mediator. This results in vasodilation and increased leakiness of the blood vessels, allowing additional immune cells (especially macrophages and neutrophils) to move out of the bloodstream and into the tissue. Inflammation is particularly useful against extracellular pathogens, including bacteria, fungi, and parasites.
Describe neutrophils
Part of the innate immune system, neutrophils are the most populous leukocyte in blood and are very short-lived (a bot more than five days). These cells are phagocytic, like macrophages, and target bacteria (the presence of bacteria activates them). Neutrophils can follow bacteria using chemotaxis; in this case, the neutrophil senses products given off by bacteria once they have been opsonized (marked with an antibody from a B-cell). Other cells, like natural killer cells, macrophages, monocytes, and eosinophils, also contain receptors for antibodies and can attack opsonized bacteria. Note: Dead neutrophil collections are responsible for the formation of pus during an infection.
The initial filtration step in the glomerulus of the mammalian kidney occurs primarily by:
Passive flow due to a pressure difference The initial filtration in the glomerulus occurs as blood pressure forces the fluid from the glomerulus into the lumen of Bowman's capsule
Describe passive immunity
Passive immunity results from the transfer of antibodies to an individual. The immunity is transient because only the antibodies, not the plasms cells that produce them, are given to the individual. Natural examples are the transfer of antibodies across the placenta during pregnancy to protect the fetus and the transfer of antibodies from a mother to her nursing infant through breast milk. In some cases of exposure, such as to the rabies virus or tetanus, intravenous immunoglobulin may be given to prevent the pathogen from spreading.
What is the difference between penetrance and expressivity in genes?
Penetrance refers to the proportion of the population with a given genotype who actually express the phenotype. Expressivity refers to the different manifestations of the same genotype across the population. If expressivity is constant, then all individuals with a given genotype express the same phenotype. If expressivity is variable, then individuals with the same genotype may have different phenotypes.
Describe peptide bond formation
Peptide bond formation is an example of a condensation or dehydration reaction because it results in the removal of a water molecule (it can also be viewed as an acyl substitution reaction): The electrophilic carbonyl carbon on the first amino acid gets attacked by the nucleophilic amino group on the second amino acid.
Describe peptide hormones
Peptide hormones are all derived from larger precursor polypeptides that are cleaved during posttranslational modification. These smaller units are transported to the Golgi Apparatus for further modifications that activate the hormones and direct them to the correct locations in the cell. Such hormones are released by exocytosis after being packaged into vesicles.
Describe peroxisomes
Peroxisomes contain hydrogen peroxide. One of the primary functions of peroxisomes is the breakdown of very long chain fatty acids via beta-oxidation. Peroxisomes participate in the synthesis of phospholipids and contain some of the enzymes involved in the PPP.
What allows cells to carry out phagocytosis?
Phagocytosis requires that the cell change shape dramatically as it surrounds and engulfs large extracellular particles. Microtubules are one of the cytoskeletal elements that help determine cell shape. Thus this function relies on the ability of the microtubules to disassemble and reorganize.
Draw Phenylalanine
Phe; F
What is the rate limiting enzyme of glycolysis?
Phosphofructokinase-1 (PFK-1)
When lipids leave the stomach, what stages of digestion have been accomplished? What enzymes are added to accomplish the next phase?
Physical digestion is accomplished in the mouth and the stomach, reducing the particle size. Beginning in the small intestine, pancreatic lipase, colipase, cholesterol esterase, and bile assist in the chemical digestion of lipids. In the more distal portion of the small intestine absorption occurs.
What are plasmids?
Plasmids are small loops of extra DNA that aren't part of the chromosome. Plasmids contain genes for things like drug resistance and can be passed between bacteria. They carry DNA that is NOT necessary for the survival of the prokaryotes and therefore is NOT considered part of the genome of the bacterium.
Describe positive sense viruses
Positive sense viruses involves single stranded RNA and implies that the genome may be directly translated to functional proteins by the ribosomes of the host cell, just like mRNA. "Is synthesis direct? Positive."
Describe postzygotic mechanisms or reproductive isolation
Postzygotic mechanisms allow for gamete fusion but yield either nonviable or sterile offspring. These mechanisms include hybrid inviability (formation of a zygote that cannot develop to term), hybrid sterility (forming hybrid offspring that cannot reproduce), and hybrid breakdown (forming first-generation hybrid offspring that are viable and fertile, but second generation offspring that are inviable or infertile).
Describe prezygotic mechanisms of reproductive isolation
Prezygotic mechanisms prevent the formation of a zygote completely. Examples include temporal isolation (breeding at different times), ecological isolation (living in different niches with the same territory), behavioral isolation ( a lack of attraction between members of the two species due to difference in pheromones, courtship displays, and so on), reproductive isolation (incompatibility of reproductive anatomy), or gametic isolation ( intercourse can occur, but fertilization cannot).
What are the two methods of reproductive isoltaion?
Prezygotic or postzygotic: Prezygotic mechanisms prevent the formation of the zygote completely Postzygotic mechanisms allow for gamete fusion but yield either nonviable or sterile offspring
Why doesn't sexual development occur until after puberty?
Prior to puberty, the hypothalamus restricts production of gonadotropin-releasing hormone (GnRH). At the start of puberty, this restriction is lifted as the hypothalamus restricts production of gonadotropic-releasing hormone (GnRH). At the start of puberty, this restriction is lifted as the hypothalamus releases pulses of GnRH which can trigger the anterior pituitary gland to synthesize the release of FH and LH.
Draw and describe Proline
Pro; P Proline is unique in that it forms a cyclic amino acid. In all other amino acids, the amino group is attached only to the alpha-carbon. In proline, however, the amino nitrogen becomes part of the side chain, forming a five-membered ring.
What are the professional antigen presenting cells?
Professional antigen-presenting cells include macrophages, dendritic cells in the skin, some B-cells. and certain activated epithelial cells.
Describe progesterone's role in female sexual development
Progesterone is secreted by the corpus luteum (the remains of the ovarian follicle following ovulation) in response to LH. Progesterone is involved in the development and maintenance of the endometrium but not in the initial thickening of the endometrium (that's the role of estrogen). Note: By the end of the first trimester of a pregnancy, progesterone is supplied by the placenta as the corpus luteum atrophies and ceases to function.
Describe prolactin
Prolactin is more important in females than in males; it stimulates milk production in the mammary glands. The high levels of estrogen and progesterone allow for the development of milk ducts in preparation for lactation, but it is not until shortly after the expulsion of the placenta, when estrogen, progesterone, and dopamine levels drop, that the block on milk production is removed and lactation actually begins -- prolactin is inhibited by dopamine (PIF) from the hypothalamus
What happens in prophase?
Prophase is the first phase in mitosis. The 1st step in prophase is the condensation of the chromatin into chromosomes. Also, the centriole pairs separate and move towards opposite poles of the cell (they are located outside of the nucleus in a region known as the centrosome). Once the centrioles migrate to opposite poles of the cell, they begin to form spindle fibers, which are made of microtubules. Some microtubules form asters that anchor the centrioles to the cell membrane. The nuclear membrane then dissolves, allowing the spindle fibers to connect to the chromosomes. Lastly, the nucleoli becomes less distinct and may disappear completely.
Describe prostaglandins
Prostaglandins are produced by almost all cells in the body. These 20 carbon molecules are unsaturated carboxylic acids derived from arachidonic acid and contain one carbon ring. They act as paracrine or autocrine signaling molecules. In many tissues, the biological function of prostaglandins is to regulate the synthesis of cyclic adenosine monophosphate (cAMP),which is a ubiquitous intracellular messenger. In turn, cAMP mediates the actions of many other hormones. Downstream effects of prostaglandins include powerful effects on smooth muscle function, influence over the sleep-wake-cycle. and the elevation of body temperature associated with fever and pain. Note: Nonsteroidal anti-inflammatory drugs (NSAID) like aspiring inhibit the enzymes cyclooxygenase (COX) which aids in the production of prostaglandins.
NSAIDs block prostaglandin production in order to reduce pain and inflammation. What do prostaglandins do to bring about these symptoms?
Prostaglandins regulate the synthesis of cAMP, which is involved in many pathways, including those that derive pain and inflammation.
What is the function of proteases?
Proteases break down proteins to amino acids.
When the body is extremely energy-deprived, it will use protein as an energy source. How is this done?
Protein obtained from diet or from the body (during prolonged fasting or starvation) may be used as an energy source. Body protein is catabolized primarily in muscle and liver. Amino acids released from proteins usually lose their amino group through transamination or deamination. The remaining carbon skeleton can be used for energy. The amino groups removed by transamination or deamination constitute a potential toxin to the body in the form of ammonia and must be excreted safely. The urea cycle occurs in the liver and is the body's primary way of removing excess nitrogen from the body. Note: amino acids are classified by their ability to turn into specific metabolic intermediates: glucogenic amino acids (all but leucine and lysine) can be converted into glucose through gluconeogenesis; ketogenic amino acids (leucine and lysine, as well as isoleucine, phenylalanine, threonine, tryptophan, and tyrosine, which are also glucogenic as well) can be converted into acetyl-CoA and ketone bodies.
Describe isoelectric focusing
Proteins can be separated n the basis of their isoelectric point (pI) (the pH at which the protein or amino acid is electrically neutral, with an equal number of + and - charges). The mixture of proteins is placed in a gel with a pH gradient (acidic gel at the positive anode, basic gel at the negative cathode, and neutral in the middle). An electric field is then generated across the gel. Proteins that are positively charged will begin migrating toward the cathode and protons that are negatively charged will begin migrating towards the anode. As the protein reaches the portion of the gel where pH = the protein's pI, the protein takes on a neutral charge and wills top moving.
Describe proteolysis
Proteolysis (the breakdown of proteins) begins in the stomach with pepsin and continues with the pancreatic proteases trypsin, chymotrypsin, and carboxypeptidases A and B, all of which are secreted as zymogens. Protein digestion is completed by the small intestinal brush-border enzymes dipeptidase and aminopeptidase. The main end-products of protein digestion are amino acids, dipeptides, and tripeptides. Absorption of amino acids and small peptides through the luminal membrane is accomplished by secondary active transport liked to sodium. At the basal membrane, simple and facilitated diffusion transports amino acids into the bloodstream.
Describe pyruvate carboxyalse
Pyruvate carboxylase is a mitochondrial enzyme that is activated by acetyl-CoA (from beta-oxidation). The product, oxaloacetate (OAA), is a citric acid cycle intermediate and cannot leave the mitochondrion. Rather, it is reduced to malate, which can leave the mitochondria via the malate-aspartate shuttle. Once in the cytoplasm, malate is oxidized to OAA. The fact that acetyl-coA activates pyruvate carboxylase is an important point. Acetyl-CoA inhibits pyruvate dehydrogenase because a high level of acetyl-CoA implies that the cell is energetically satisfied and need not run the citric acid cycle in the forward direction; in other words, the cell should stop burning glucose. Rather pyruvate will be shunted through pyruvate carboxylase to help generate additional glucose through gluconeogenesis--note that the source of acetyl-CoA is not from glycolysis and pyruvate dehydrogenase in this case but from fatty acids. Thus to produce glucose in the liver during gluconeogenesis, fatty acids must be burned to provide this energy, stop the forward flow of the citric acid cycle, and produce massive amounts of OAA that can eventually lead to glucose production for the rest of the body.
Describe the pyruvate dehydrogenase complex
Pyruvate dehydrogenase is a complex of enzymes carrying out multiple reactions in succession. It relies on multiple cofactors and coenzymes such as thiamine pyrophosphate, lipoic acid, CoA, FAD, and NAD+. Insufficient amounts of any of these cofactors or coenzymes can result in metabolic derangements. Pyruvate dehydrogenase is inhibited by its product acetyl CoA: the build-up of acetyl-CoA causes a shift in metabolism where pyruvate is no longer converted into acetyl-CoA to enter the citric acid cycle, but rather into oxaloacetate to enter gluconeogenesis.
Describe pyruvate kinase
Pyruvate kinase catalyzes a substrate-level phosphorylation of ADP using the high energy substrate phosphoenolpyruvate (PEP). Pyruvate kinase is activated by F16BP from the PFK-1 reaction. This is referred to as feed forward activation, meaning that the product of an earlier reaction of glycolysis (F16BP) stimulates or prepares a later reaction in glycolysis (by activating pyruvate kinase).
Describe dipeptidases
Released by the duodenum, dipeptidases cleave the peptide bonds of dipeptides to release free amino acids.
Describe enteropeptidase
Released in the duodenum, enteropeptidase is an enzyme critical for activation of trypsinogen, a pancreatic protease, to trypsin. Trypsin then initiates an activation cascade. Note: enteropeptidase can also activate procaboxypeptidases A and B to their active forms,
Describe the initiation of transcription
RNA is synthesized by a DNA-dependent RNA polymerase; RNA polymerase locates genes by searching for specialized DNA regions known as promoter regions. In eukaryotes, RNA polymerase II is the main player in transcribing mRNA, and its binding site in the promoter region is known as the TATA box, named for its high concentration of thymine and adenine bases. Transcription factors help the RNA polymerase locate and bind to this promoter region of the DNA, helping to reestablish where transcription will start. Note: Unlike DNA polymerase III, RNA polymerase does not require a primer to start generating a transcript.
how would delivering RNA complementary to a viral mRNA into all infected cells help stop an infection causes by a persistent virus?
RNA that is complementary to viral mRNA would base pair with the mRNA, forming an RNA-mRNA hybrid. Once the mRNA complexes with the anti-sense RNA, the mRNA cannot be translated, ad therefore no viral proteins could be produced. If no viral proteins can be produced, the virus would be unable to selectively block the transcription of host genes coding for specialized functions, and this might also render the virus susceptible to the host immune response.
Nucleic acids are classified according to the pentose they contain. If the pentose is ribose, the nucleic acid is _______; if the pentose is deoxyribose the nucleic acid is ______.
RNA; DNA
How do you calculate the respiratory quotient?
RQ= CO2 produced/ O2 consumed *the respiratory quotient for carbohydrates is around 1.0 while the respiratory quotient for lipids is around 0.7
What happens in the third trimester?
Rapid growth and brain development continue and there is a transfer of antibodies to the fetus via the placenta
What process allows the inheritance of one gene to be independent of the inheritance of all others? (Mendel's Second Law)
Recombination in prophase I
Describe erythrocytes
Red blood cells are unique in a number of ways, and their modifications reflect the special role they play in the human body: * Red blood cells are biconcave, or indented on both sides, which serves a dual purpose. First, this shape assists them in traveling through tiny capillaries. Second, it increases the cell's surface area which increases gas exchange. *Red blood cells are also unique in that, when they mature, the nuclei, mitochondria, and other membrane-bound organelles are lost. The loss of organelles makes space for the molecules of hemoglobin. In addition, the loss of mitochondria in particular means that the red blood cell does not consume the oxygen it is carrying before it is delivered to the peripheral tissues--thus, red blood cells do not carry out oxidative phosphorylation to generate ATP; rather, they rely entirely on glycolysis for ATP, with lactic acid as the main by-product. Also, because red blood cells lack nuclei, they are unable to divide--erythrocytes can live for 120 days in the bloodstream before cells in the liver and spleen phagocytize senescent (old) red blood cells to recycle them for their parts.
Describe repressible operon systems
Repressible systems allow the constant production of a protein product. In contrast to the inducible system. the repressor made by the regulator gene is inactive until it binds to a corepressor. This complex then binds the operator site to prevent further transcription. Repressible systems tend to serve as negative feedback; often, the final structural product can serve as the corepressor. An example of this is the trp operon
Describe restriction enzymes
Restriction enzymes (restriction endonucleases) are enzymes that recognize specific double-stranded DNA sequences. These sequences are palindromic, meaning that the 5' to 3' sequence of one strand is identical to the 5' to 3' sequence of the other strand (in antiparallel orientation). Restriction enzymes are isolated from bacteria, which are their natural source. In bacteria, they act as part of a restriction and modification system that protects the bacteria from inflection by DNA viruses. Once a specific sequence has been identified, the restriction enzyme can cut through the backbones of the double helix. Some restriction enzymes produce offset cuts, yielding sticky ends on the fragments. Sticky ends are advantageous in facilitating the recombination of a restriction fragment with the vector DNA. The vector of choice can also be cut with the same restriction enzyme, allowing the fragments to be inserted directly into the vector. DNA vectors contain at least one sequence, if not many, recognized by restriction enzymes. A vector also requires an origin of replication and at least one gene for antibiotic resistance to allow for selection of colonies with recombinant plasmids.
Describe retroviruses
Retroviruses are enveloped, single-stranded RNA virus, the virion contains two identical RNA molecules. These viruses carry an enzyme known as reverse transcriptase, which synthesizes DNA from single stranded RNA. The DNA integrate into the host cell genome, where it is replicated and transcribed as if it were the host cell's own DNA. Integration of the genetic material into the host cell genome allows the cell to be infected indefinitely, so the only way to remove the infection is to kill the infected cell . Ex: HIV.
Describe rRNA
Ribosomal RNA is synthesized in the nucleolus and functions as an integral part of the ribosomal machinery used during protein assembly in the cytoplasm. Many rRNA molecules function as ribozymes; that is, enzymes made of RNA molecules instead of peptides. rRNA help catalyze the formation of peptide bonds and is also important in splicing out its own introns within the nucleus.
Describe SDS-PAGE electrophoresis
SDS-PAGE denatures proteins so the functional protein cannot be recaptured. It separates proteins on the basis of relative molecular mass ALONE. It starts with the premise of PAGE but adds sodium dodecyl-sulfate (SDS), a detergent that disrupts all noncovalent interactions. It binds to proteins and creates large chains with negative charges, thereby neutralizing the proteins' original charge (the proteins will have uniformly negative charges) and denaturing the protein. As the proteins move through the gel, the only variables affecting their velocity are E and f (which depend on mass).
What is saponification?
Saponification is the ester hydrolysis of triacylglycerols using a strong base. Traditionally, the base that is used is lye, the common name for sodium or potassium hydroxide. The result is the basic cleavage of the fatty acid, leaving the sodium salt of the fatty acid and glycerol. The fatty acid salt is what we know as soap.
How are sarcomeres arranged?
Sarcomeres are attached end-to-end to form myofibrils. Myofibrils are surrounded by a covering known as the sarcoplasmic reticulum (SR), a modified endoplasmic reticulum that contains a high concentration of Ca2+ ions. The sarcoplasm is a modified cytoplasm located just outside the sarcoplasmic reticulum. The cell membrane of a myocyte is known as the sarcolemma.
Describe saturated fatty acids
Saturated fatty acids are the main components of animal fats and tend to exist as solids at room temperature. Saturated fats are found in processed foods and are considered less healthy. When incorporates into phospholipid membranes, saturated fatty acids decrease the overall membrane fluidity.
Describe secretin
Secretin is a peptide hormone that causes pancreatic enzymes to be released into the duodenum. It also regulates the pH of the digestive tract by reducing HCl secretion from parietal cells and increasing bicarbonate secretion from the pancreas. Secretin is also an enterogastrone, a hormone that slows motility through the digestive tract. Slowing of motility allows increased tome for digestive enzymes to act on chyme -- especially fats.
Where are secretory proteins synthesized?
Secretory proteins are synthesized and folded in The Rough ER
Is DNA replication conservative or semi-conservative?
Semi-conservative because of new daughter strands.
Describe the production seminal fluid
Seminal fluid is prodiced through a combined effort by the seminal vesicles, prostate gland, and bulbourethral gland: *The seminal vesicles contribute fructose to nourish sperm *Both the seminal vesicles and prostate gland give the fluid mildly alkaline properties so the sperm can survive in the relative acidity of the female reproductive tract *The bulbourethral (Cooper's) gland produces a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal Note: the combination of sperm and seminal fluid is known as semen
Draw Serine
Ser; S
What are the polar amino acids?
Serine (S), Threonine (T) Cysteine(C), Tyrosine (Y), Asparagine (N), Glutamine (Q) Stop Talking, Call Your New Queen Their side chains DO NOT gain or lose protons with changes in pH. Only their main amide and carboxylic acid do
Which amino acids can be phosphorylated?
Serine (S), threonine (T), and tyrosine(Y) STY
How do fatty acids get into the mitochondria?
Short-chain fatty acids (two or four carbons) and medium chain fatty acids (six to twelve carbons) diffuse freely into mitochondria, where they are oxidized. In contrast, while long-chain fatty acids (14 to 20 carbons) are also oxidized in the mitochondria, they require transport via a carnitine shuttle--thus carnitine acyltransferase I is the rate limiting enzyme of fatty acid oxidation. Note: very long chain fatty acids (over 20 carbons) are oxidized elsewhere in the cell.
How are fats taken up by the jejunum and ileum?
Short-chain fatty acids will follow the same process as carbohydrates and amino acids by diffusing directly into the interstitial capillaries. These fatty acids do not require transporters because they are non-polar, so they can easily transverse the cellular membrane. Larger fats, glycerol, and cholesterol move separately into the interstitial cells but then reform into triglycerides. The triglycerides and esterified cholesterol molecules are packaged into chylomicrons. Rather than entering the bloodstream, chylomicrons enter the lymphatic circulation through lacteals, small vessels that form the beginning of the lymphatic system. These lacteals converge and enter the venous circulation at the thoracic duct in the base of the neck, which empties into the left subclavian vein.
In an enhancer, what are the differences between signal molecules, transcription factors, and response elements?
Signal molecules include steroid hormones and second messengers, which bind to their receptors in the nucleus. These receptors are transcription factors that use their DNA-binding domains to attach to a particular sequence in DNA called a response element. Once bonded to the response element, these transcription factors can then promote increased expression of the relevant gene.
What are hormones?
Signaling molecules that are secreted directly into the bloodstream to distant targets. At target tissues, hormones bind to receptors, inducing a change in gene expression or cellular functioning. Hormones can be peptides, steroids, or amino acid derivatives.
What is the function of memory T -cells?
Similar to memory B-cells, these cells li in wait until the next exposure to the same antigen. When activated, they carry out a more robust and rapid response
How are carbohydrates and amino acids taken up by the jejunum and ileum?
Simple sugars such as glucose, fructose, and galactose, and amino acids are absorbed by secondary active transport and facilitated diffusion into the epithelial cell s lining the small intestine. Then, these substances move across the epithelial cell membrane into the intestinal capillaries. Blood is constantly passing by the epithelial cells carrying the carbohydrate and amino acid molecules away. This creates a concentration gradient such that the blood always has a lower concentration of monosaccharides and amino acids than inside the epithelial cells. Thus, simple carbohydrates and amino acids diffuse from the epithelial cells into the capillaries. The absorbed molecules then go to the liver via the hepatic portal circulation.
How do prokaryotes carry out ATP synthesis?
Since prokaryotes lack organelles, they lack mitochondria. They instead use their cell membrane for the ETC chain and generation of ATP.
Why are proteins a good cellular scaffold?
Since they exhibit low reactivity they are very stable under physiological conditions
Describe skeletal muscle
Skeletal muscle is responsible for voluntary movement and is therefore innervated by the somatic nervous system. Due to the arrangement of actin and myosin into repeating units called sarcomeres, it appears striped or striated when viewed microscopically. Skeletal muscle is multinucleated because it is formed as individual muscle cells fuse into long rods during development.
What can diffuse freely through the cell membrane?
Small, nonpolar, lipid-soluble particles, and water. Large, polar, or charged particles cannot. Note: hydrophobic residues are also nonpolar
Describe the structure of smooth muscle
Smooth muscle cells have a single nucleus located in the center of the cell. Just like skeletal muscle, smooth muscle cells contain actin and myosin, but the fibers are not as well organized, so striations can not be seen (smooth muscle is NOT striated). Compared to skeletal muscle smooth muscle is capable of more sustained contractions; a constant state of low-level contraction, as may be seen in the blood vessels, is called tonus. Smooth muscle can actually contract without nervous system input in what is known as myogenic activity. In this case, the muscle cells contract directly in response to stretch to other stimuli.
In a species of beetle, red body color is dominant to brown. Two red beetles are crossed and produce 31 red and 9 brown offspring (F1 generation). If two red F1 beetles are crossed, what is the probability that both red and brown beetles will appear in the F2 generation? (Note: Assume Mendelian inheritance patterns.) A. 4/9 B. 1/2 C. 2/3 D. 3/4
Solution: The correct answer is A. The answer to this question is A because given Mendelian inheritance patterns, a 3:1 ratio of F1 offspring means that the original crossed beetles are both heterozygotes, and the F1 offspring are 25% red (homozygous dominant), 50% red (heterozygous), and 25% brown (homozygous recessive). If two red F1 beetles are crossed and both red and brown beetles appear in the F2 generation, the F1 red beetles that were crossed must both be heterozygotes. The probability that, of the red F1 beetles, both were heterozygous is 2/3 × 2/3, or 4/9 (only red beetles were selected from and 2/3 of the red F1 beetles were heterozygous).
Which of the following statements gives the most fundamental reason why ornithine is unlikely to be found in proteins synthesized in vivo? A. There is no codon for it in the standard genetic code. B. It cannot form a peptide bond. C. It is not available in the diet. D. It has a net positive charge in aqueous solution.
Solution: The correct answer is A. The answer to this question is A, because without a corresponding codon in the genetic code, an amino acid cannot take part in the process of protein translation from an mRNA transcript.
In human females, mitotic divisions of oogonia that lead to formation of presumptive egg cells (primary oocytes) occur between: A. fertilization and birth only B. birth and puberty only C. fertilization and puberty only D. puberty and menopause only
Solution: The correct answer is A. The question asks the examinee to identify the stages in the human female life cycle between which all the mitotic divisions that lead to primary oocytes occur. These stages occur in the following order: fertilization, birth, puberty, menopause. All of the mitotic divisions that form primary oocytes occur prior to birth. Thus, A is the best answer.
A certain bacterium was cultured for several generations in medium containing 15N, transferred to medium containing 14N, and allowed to complete two rounds of cell division. Given that the bacterium's genome mass is 5.4 fg when grown in 14N media and 5.5 fg when grown in 15N medium, individual bacteria with which of the following genome masses would most likely be isolated from this culture? A. 5.4 fg only B. 5.4 fg and 5.45 fg C. 5.4 fg and 5.5 fg D. 5.45 fg only
Solution: The correct answer is B. The answer to this question is B because DNA replication is semi-conservative. Therefore, after the first round of cell division the genome mass in each bacterium will be 5.45 fg (one DNA strand will contain 15N and the other strand 14N). Following the second round of cell division, half of the bacteria will have a genome mass of 5.4 fg (14N exclusively) and the other half a mass genome of 5.45 fg (14N in one DNA strand and 15N in the other).
A homodimeric protein was found to migrate through SDS polyacrylamide gel electrophoresis (SDS-PAGE) with a mobility that matched that of a 45-kDa standard. What change in the experiment would increase the chances of observing the mobility expected for the 22.5-kDa monomer? A. Increasing the gel running time B. Adding a reducing agent C. Using a higher voltage D. Removing the SDS
Solution: The correct answer is B. The answer to this question is B because adding a reducing agent would eliminate any disulfide bridges and allow the monomers to run separately-thus leading to a migration expected for the 22.5-kDa protein.
The lung cells of heavy smokers would be expected to have greatly increased concentrations of cP-450 and: A. DNA sequences that code for cP-450. B. mRNA sequences that code for cP-450. C. rRNA that process cP-450. D. tRNA that are specific for cysteine.
Solution: The correct answer is B. The answer to this question is B, because protein levels relate most directly to mRNA levels.
Describe telomerase
Telomerase is a reverse transcriptase that is able to synthesize the end of chromosomes and prevent cell aging--it adds back telomeres
A drug that binds to tubulin molecules of plant cells and prevents the cells from assembling spindle microtubules would most likely cause the resulting plants or plant cells to have: A. greater genetic variability than the parent plants B. More than two sets of chromosomes C. A stronger cell wall thanks to more tubulin D. Independent movement because of excess tubulin
Solution: The correct answer is B. The fibers that attach to the chromosomes in mitosis and form the mitotic spindle (the spindle fibers) are microtubules. They are assemblies of tubulin proteins. Disruption of the mitotic spindle by drugs prevents the proper segregation of chromosomes into the daughter cells and usually results in unequal numbers being distributed to the two daughter cells. Many of the resulting plant cells would have more than two sets of chromosomes, thus making answer choice B the correct answer. While a plant might differ from its parent plants in the number of chromosomes, it would contain the same genes. Only in a limited sense would it have more genetic variability. Thus, answer choice A is incorrect. Answer choice C is incorrect because tubulin is not found in the cell wall. Answer choice D is incorrect because tubulin has only a minor role in motility, thus making independent movement unlikely.
Inhibition of phosphofructokinase-1 by ATP is an example of: I. allosteric regulation. II. feedback inhibition. III. competitive inhibition. A. I only B. III only C. I and II only D. II and III only
Solution: The correct answer is C. The answer to this question is C because ATP, the end product of glycolysis, downregulates through feedback inhibition the activity of phosphofructokinase-1 by binding to a regulatory site other than the active site of the enzyme (allosteric regulation). In contrast, competitive inhibition involves competition for binding to the active site.
A large carbohydrate is tagged with a fluorescent marker and placed in the extracellular environment around a macrophage. The macrophage ingests the carbohydrate via phagocytosis. Which cellular structure is most likely to be fluorescently labeled upon viewing with a light microscope soon after phagocytosis? A. Nucleus B. Golgi apparatus C. Lysosome D. Endoplasmic reticulum
Solution: The correct answer is C. The answer to this question is C because when a macrophage ingests foreign material, the material initially becomes trapped in a phagosome. The phagosome then fuses with a lysosome to form a phagolysosome. Inside the phagolysosome, enzymes digest the foreign object. Of the cell structures listed, the labeled carbohydrate is most likely to be microscopically visualized within a lysosome (phagolysosome).
If an artery that supplies blood to a lung lobe was blocked but ventilation to the lobe was unaffected, how would alveolar gas (PO2 and CO2) partial pressures change?
Solution: The correct answer is C. If the blood flow to an alveolus were blocked there would be no flow of hemoglobin-rich red blood cells to take away O2 and no influx of CO2 from the blood. As a result the air in the alveolus would become more like that of the atmosphere. It would acquire a higher PO2 and a lower PCO2.
The cell type in the male reproductive system that is most analogous to the female ovum is the: A. spermatogonium B. Primary spermatocyte C. spermatid D. spermatozoon
Solution: The correct answer is D. The mature ovum is the female gamete that has completed meiosis and contains the haploid number of maternally derived chromosomes. This makes it most analogous to spermatozoa, the mature male gametes that contain the haploid number of paternally derived chromosomes. Thus, D is the best answer.
After the depletion of hepatic glycogen in newborns, which compounds can be used as precursors to sustain the blood glucose level? I. Acetyl-CoA II. Lactate III. Oxaloacetate IV. α-Ketoglutarate A. I and II only B. II and III only C. I, II,and IV only D. II, III, and IV only
Solution: The correct answer is D. The answer to this question is D because among the listed options, only lactate, oxaloacetate, and α-ketoglutarate are used as starting materials in gluconeogenesis.
An enzyme is more effectively inhibited by uncompetitive inhibitors when: I. the substrate concentration is decreased. II. the substrate concentration is increased. III. the inhibitor concentration is increased. A. I only B. III only C. I and III only D. II and III only
Solution: The correct answer is D. The answer to this question is D because uncompetitive inhibitors bind their target enzymes only when the substrate is first bound to the enzyme. Since at higher substrate concentrations, the substrate-enzyme complex are more abundant, the uncompetitive inhibitor will work most effectively when the substrate concentration is the highest. Additionally, an increase in the inhibitor concentration results in increased enzyme binding and inhibition.
The rate of a typical enzymatic reaction is increased by which of the following changes? A. Decrease in a substrate concentration B. Increase in pH from 6.8 to 7.4 C. Increase in the energy of activation D. Increase in temperature from 20°C to 37°C
Solution: The correct answer is D. The answer to this question is D because while the optimum pH value varies greatly from one enzyme to another, the optimum temperature for enzymes is normally 37 °C.
Describe somatostatin
Somatostatin is an inhibitor of both insulin and glucagon secretion. High blood glucose and amino acid concentrations stimulate its secretion. Somatostatin is also produced by the hypothalamus. where it decreases growth hormone secretion in addition to its effects on insulin and glucagon
Describe the process of spermatogenesis
Spermatogenesis is the formation of haploid sperm through meiosis. It occurs in the seminiferous tubules as follows: 1. We start with diploid stem cells called spermatogonia. 2. After replicating their genetic material (S stage), the spermatogonia develop into primary spermatocytes. 3. The first meiotic division will result in haploid secondary spermatocytes which will then undergo smeiosis II to generate haploid spermatids. 4. Finally, the spermatids undergo maturation to become mature spermatozoa. Note: This process means that spermatogenesis results in four functional sperm for each spermatogonium.
Describe sphingolipids
Sphingolipids have a sphingosine or sphingoid (sphingosine-like) backbone. These molecules also have long-chain, nonpolar fatty acid tails and polar head groups. Many sphingolipids are also phospholipids because they contain a phosphodiester linkage. However, other sphingolipids contain glycosidic linkages to sugars any lipid linked to a sugar can be termed a glycolipid. Sphingolipids are thus divided into four major subclasses differing by their head group: ceramide, sphingomyelins, cerebrosides, globosides, and gangliosides. SPHIGNOLIPIDS DO NOT CONTAIN GLYCEROL!
Describe sphingomyelins and draw an example
Sphingomyelins are the major class of sphingolipids that are also phospholipids (sphingophospholipids). These molecules have either phosphatidylcholine or phosphatidylethanolamine as a head group and thus contain a phosphodiester bond. Sphingomyelin head groups have no net charge. As the name implies, sphingomyelins are major components in the plasma membrane of cells producing myelin (oligodendrocytes and Schwann cells), the insulating sheath for axons.
Describe startch
Starches are polysaccharides that are more digestible by humans because they are linked alpha-D-glucose monomers. Plants predominantly store starch as amylose, a linear glucose polymer linked via alpha-1,4 glycosidic bonds. Another type of starch is amylopectin, which starts off with the same type of linkage that amylose exhibits but also contains branches via alpha-1,6 glycosidic bonds. Note: Iodine is a well-known reagent that tests for the presence of starch and does so by fitting inside the helix conformation amylose typically makes, forming a starch-iodine complex.
Describe the structure of steroids
Structurally, steroids are metabolic derivatives of terpenes. Steroids are characterized by having four cycloalkane rings fused together: 3 cyclohexane and one cyclopentane. Steroid functionality is determined by the oxidation status of these rings, as well as the functional groups they carry. It is important to note that the large number of carbons and hydrogens make steroids nonpolar, like other lipids.
Describe the breakdown of amylose and amylopectin
Starches like amylose and amylopectin are broken down by enzymes in the body and are used as a source of energy. Amylose is degraded by alpha-amylase and beta-amylase: Beta-amylase cleaves amylose at the nonreducing end of the polymer (the end with acetal) to yield maltose. Alpha-amylase cleaves randomly along the chain to yield shorter polysaccharide chains, maltose, and glucose. Note: Because amylopectin is so branched debranching enzymes help degrade the polysaccharide chain.
Describe the first reaction in the TCA
Step 1 -- Citrate formation: First, acetyl-CoA and oxaloacetate undergo a condensation reaction to form citryl-CoA, an intermediate. Then the hydrolysis of citryl-CoA yields citrate and CoA-SH. This reaction is catalyzed by citrate synthase.
Describe the second reaction in the TCA
Step 2 -- citrate isomerized to isocitrate Achiral citrate is isomerized to one of four possible isomers of isocitrate. First, citrate binds at three points to the enzyme aconitase. Then water is lost from citrate yielding cis-aconitate. Finally, water is added back to form isocitrate. The enzyme s a metalloprotein that requires Fe2+. This process results in the switching of a hydrogen and a hydroxyl group. Overall, this step is necessary to facilitate the subsequent oxidative decarboxylation.
Describe the third reaction in the TCA
Step 3 -- alpha-ketoglutarate and CO2 formation Isocitrate is first oxidized to oxalosuccinate by isocitrate dehydrogenase. Then oxalosuccinate is decarboxylated to produce alpha-ketoglutarate and CO2. This is a very important step because isocitrate dehydrogenase is the rate-limiting enzyme of the citric acid cycle. The first two carbons from the cycle is lost here. This is also the first NADH produced from intermediates in the cycle.
Describe the fourth reaction in the TCA
Step 4 -- Succinyl-CoA and CO2 formation: These reactions are carried out by the alpha-ketoglutarate dehydrogenase complex, which is similar in mechanism, cofactors, and coenzymes to the pyruvate dehydrogenase (PDH) complex. In the formation of succinyl-CoA, alpha-ketoglutarate and CoA come together and produce a molecule of carbonized. This carbon dioxide represents the second and last carbon lost from the cycle. Reducing NAD+ produces another NADH.
Describe the fifth reaction in the TCA
Step 5 -- Succinate Formation: Hydrolysis of the thioester bond on succinyl-CoA yields succinate and CoA-SH, and is coupled to the phosphorylation of GDP to GTP. This reaction is catalyzed by succinyl-CoA synthetase. Once GTP is formed, an enzyme called nucleosidediphosphate kinase catalyzes phosphate transfer from GTP to ADP, thus producing ATP. Note that this is the only rime in the entire citric acid cycle that ATP is produced directly; ATP production occurs predominately within the ETC.
Describe the sixth reaction in the TCA
Step 6 -- Fumarate formation: This is the only step of the citric acid cycle that doesn't take place in the mitochondrial matrix; instead, it occurs on the inner membrane. Here's why: succinate undergoes oxidation to yield fumarate. This reaction is catalyzed by succinate dehydrogenase. Succinate dehydrogenase is considered a flavoprotein because it is covalently bonded to FAD, the electron acceptor in this reaction. This enzyme is an integral protein on the inner mitochondrial membrane. As succinate is oxidized to fumarate, FAD is reduced to FADH2. Each molecule of FADH2 then passes the electrons it carries to the ETC, which eventually leads to the production of 1.5ATP (unlike NADH, which will give rise to 2.5 ATP). FAD is the electron acceptor in this reaction because the reducing power of succinate is not great enough to reduce NAD+.
Describe the seventh reaction in the TCA
Step 7 -- Malate formation: The enzyme fumarase catalyzes the hydrolysis of the alkene bond in fumarate, thereby giving rise to malate. Although two enantiomers forms are possible, only L-malate dorms in this reaction.
Describe the eighth reaction in the TCA
Step 8 -- Oxaloacetate Formed Anew: The enzyme malate dehydrogenase catalyzes the oxidation of malate to oxaloacetate. A third and final molecule of NAD+ is reduced to NADH. The newly formed oxaloacetate is ready to take part in another turn of the citric acid cycle, ad we've gained all the high energy electron carrier possible from one turn of the cycle.
Describe steroid hormones
Steroid hormones are derived from cholesterol and are produced primarily by the gonads and adrenal cortex (endocrine glands). Steroid hormones have high-affinity receptors, work at low concentrations, and affect gene expression and metabolism.
How do steroid hormones travel?
Steroid hormones are not water-soluble, so they must be carried by proteins in the bloodstream to travel around the body. Some of these proteins are very specific and carry only one hormone (such as sex hormone-binding globulin), while other proteins are nonspecific (such as albumin). Note that hormones are generally inactive while attached to a carrier protein and must dissociate from the carrier to function. Therefore, levels of carrier proteins can change the levels of active hormone. For example, some conditions increase the quantity of a protein that carries thyroid hormones, thyroxine-binding globulin (TBG). This causes the body to perceive a lower level of thyroid hormone because the increased quantity of TBG binds a larger proportion of the hormone, meaning there is less free hormone available.
What are teratogens?
Substance that interfere with development, causing defects or even death of the developing embryo. Not every teratogen will have the same effect on every embryo or fetus. It is believed that unique genetics of the embryo influences the effects of the teratogen. In addition to genetics, the route of exposure, length of exposure, rate of placental transmission, and exact identity of the teratogen will also affect the outcome. A teratogen could be alcohol, prescription drugs, bacteria, viruses and environmental chemicals to name a few
Describe surfactants
Surfactants lower the surface tension at the surface of a liquid, serving as a detergent or emulsifier. This is important to how soap works. If we try to combine an aqueous solution and oil, as with vinegar and olive oil in salad dressing, these solutions will remain in separate phases. If we were to add a soap, however, the two phases would appear to combine into a single phase, forming a colloid. This occurs because of the formation of micelles: tiny aggregates of soap with the hydrophobic tails turned inward and the hydrophilic heads turned outward, thereby shielding the hydrophobic lipid tails and allowing for overall solvation. Nonpolar compounds can dissolve in the hydrophobic interior of the water-soluble micelle meaning that our cleaning agents can dissolve both water-soluble and water-insoluble messes and then wash them all away together. Note: the micelles are the cause of soap bubbles!
What type of relationship do gut bacteria have with humans?
Symbiotic: the bacteria are provided with a steady source of food, and the byproducts produced by the bacteria are beneficial to humans. For example, gut bacteria produce vitamin K and biotin (vitamin B7)
The majority of triacylglycerols stored in adipocytes originate from...
Synthesis in the liver The liver is the major metabolic organ in the body and is responsible for much of the synthesis and interconversion of fuel sources. Most of the triacylglycerols that are synthesized in the liver are transported as VLDL to adipose tissue for storage.
What are the lymphocytes?
T and B cells
Describe the development of T-cells
T-cells are produced in the bone marrow but mature in the thymus (T-cells = Thymus cells), a small gland just in front of the pericardium, the sac that protects the heart. T-cells are agents of cell-mediated immunity because they coordinate the immune system and directly kill virally infected cells.
Describe the selection process of T-cells
T-cells mature in the thymus where they undergo both positive and negative selection: Positive selection refers to allowing only the maturation of cells that can respond to the presentation of antigen on MHC (cells that cannot respond to MHC undergo apoptosis because they will not be able to respond in the periphery). Negative selection refers to causing apoptosis in cells that are self-reactive (activated by proteins produced by the organism itself). The maturation of T-cells is facilitated by thymosin, a peptide hormone secreted by thymic cells. Once the T-cell has left the thymus, it is mature but naive. Upon exposure to antigen, T-cells will also undergo colonial selection so that only those with the highest affinity for a given antigen proliferate.
What are apoproteins?
Term used for the protein when not in complex with other molecule (ex. apo-lipoprotein)
Describe terpenes
Terpenes are a class of lipids built from isoprene (C5H8) moieties and share a common structural pattern with carbons grouped in multiples of five. Terpenes are odiferous chemicals that are the metabolic precursors to steroids and other lipid signaling molecules. They have varied independent functions. Terpenes are grouped together according to the number of isoprene units present; a single terpene contains two isoprene units.
What are terpenoids?
Terpenoids are derived from terpenes via oxygenation or backbone rearrangement. They have similar odorous characteristics.
Which zone in the sarcomere does NOT change its length during muscle contraction? Why?
The A-band does not change length during muscle contraction because it is the entire length of the myosin filament. The filaments do not change length but rather slide over each other; thus, the A-band should remain a constant length during contraction
An individual with B+ blood is in an automobile accident and requires a blood transfusion. What blood types could he receive? The same individual is so thankful that after recovery he decides to donate blood. To which blood types could he donate?
The B+ person could receive blood from B+, B-, O+, or O- people. The B+ person could donate to B+, or AB+ people.
What is the difference between RNA and DNA structure?
The DNA has a hydrogen on its 2' carbon and the RNA has an alcohol on its 2' carbon
Describe the endoplasmic reticulum
The ER is a series of interconnected membranes and is continuous with the nuclear envelope. It consists of two components: The Rough ER: is studded with ribosomes which permit the translation of proteins destined for secretion directly into the lumen. The Smooth ER: lacks ribosomes and is utilized primarily for lipid synthesis and the detoxification of certain drugs and toxins. The SER also transports proteins from the RER to the Golgi apparatus.
Describe the M-Stage of the cell cycle
The M stage consists of mitosis itself along with cytokinesis. Mitosis is divided into 4 phases: prophase, metaphase, anaphase, and telophase (PMAT)
Describe the Rh factor and its role in blood
The Rh factor is a surface protein expressed on red blood cells. When left unmodified, Rh-positive (RH+) or Rh-negative (RH-) refers to the presence or absence of a specific allele called D. Rh-positivity follows autosomal dominant inheritance; one positive allele is enough for the protein to be expressed.
What does the concept of pace maker cells mean for the heart?
The SA node generates about 60-100 beats per minute, even if all innervation to the heart is cut. Neurological input to the heart is important for speeding up and slowing the rate of contraction, but not generating it in the first place.
Draw a Lineweaver-Burke plot. What information do the following intercept points correspond to? X axis Y axis slope y intercept x intercept
The X-axis is 1/[S] the Y-axis is 1/V the slope is Km/vmax the y intercept is 1/vmax the x intercept is -1/km
The rate of an enzyme-catalyzed reaction can be influenced by which of the following? I. Temperature II. pH III. Salinity
The activity of an enzyme is heavily influenced by its environment. The temperature, acidity, and salinity all have significant effects on the ability of an enzyme to carry out its function.
What's so cool about the adrenal glands?
The adrenal glands have dual embryonic origin: -The adrenal cortex is derived from the mesoderm -The adrenal medulla is derived from the ectoderm (this is because the adrenal medulla contains some nervous tissue)
Describe agranulocytes
The agranulocytes, which do not contain granules that are released by exocytosis, consist of lymphocytes and monocytes. Lymphocytes are important in the specific immune response, the body's targeted fight against particular pathogens such as viruses and bacteria. Some lymphocytes act as primary responders against an infection, while others function to maintain a long-term memory bank of pathogen recognition. These cells, in a very real sense, help our body learn from experience and are prepared to mount a fast response upon repeated exposure to familiar pathogens.
What difference between the envelopes of gram-positive and gram negative bacteria make gram-positive bacteria more susceptible to antibiotics such as penicillin?
The antibiotic penicillin targets the enzyme that catalyzes the cross-linking of peptidoglycan . Gram-positive bacteria have a thick layer of peptidoglycan and lipoteichoic acid, and contain no other membrane, whereas gram-negative bacteria have only a thin layer of peptidoglycan but also have an outer-membrane containing lipopolysaccharides and phospholipids. Penicillin and antibiotics with similar function can more easily reach and weaken the peptidoglycan layer of gram-positive bacteria.
How are archaea similar to eukaryotes? To bacteria?
The are similar to eukaryotes in the fact that they start translation with methionine, they have similar RNA polymerases, and they have histones. They are similar to bacteria in that they have singular circular chromosomes and they divide by binary fission or budding.
Describe the valves of the heart
The atria are separated from the ventricles by atrioventricular valves. Likewise, the ventricles are separated from the vasculature by the semilunar valves. These valves allow the heart muscle to create the pressure within the ventricles necessary to propel the blood forward within the circulation, while also preventing backflow of blood. The valve between the right atrium and the right ventricle is known as the tricuspid valve, while the valve between the left atrium and the left ventricle is known as the mitral or bicuspid valve. The valve that separates the right ventricle from the pulmonary circulation is known as the pulmonary valve, while the valve that separates the left ventricle from the aorta is known as the aortic valve. Both semilunar valves have 3 leaflets.
What is the difference between prokaryotic and eukaryotic replication?
The bacterial chromosome is a closed, double-stranded circular DNA molecule with a single origin of replication. Thus, there are two replication forks that move away from each other in opposite directions around the circle. The two replication forks eventually meet, resulting in the production of two identical circular molecules of DNA. Eukaryotic replication must copy many more bases compared to prokaryotes and is a slower process. In order to duplicate all of the chromosomes efficiently, each eukaryotic chromosome contains one linear molecule of double-stranded DNA having multiple origins of replication. As the replication forks move toward each other and sister chromatids are created, the chromatids will remain connected at the centromere.
Based on the formula: CO₂ (g) + H₂O (l) ↔H₂CO₃ (aq) ↔ H+(aq) + HCO₃-(aq) How does the body respond to acidosis?
The body attempts to maintain a pH between 7.35 and 7.45. When the pH is lower, and hydrogen ion concentration is higher (acidemia), acid-sensing chemoreceptors just outside the blood-brain barrier send signals to the brain to increase the respiratory rate. Further, an increasing hydrogen ion concentration will cause a shift in the bicarbonate buffer system, generating additional carbon dioxide. The respiratory centers in the brain are sensitive to this increasing partial pressure of carbon dioxide and will also promote an increase in respiratory rate.
Describe the microscopic structure of compact bone.
The bony matrix is ordered into structural units known as osteons or Haversian systems. Each of these osteons contains concentric circles of bony matrix called lamellae surrounding a central microscopic channel. Longitudinal channels (those with an axis parallel to the bone) are known as Haversian canals, while transverse channels (those with an axis perpendicular to the bone) are known as Volkmann's canals. These canals contain blood vessels, nerve fibers, and lymph vessels that maintain the health of the bone --al of this is why it hurts to break a bone. Between the lamellar rings are small spaces known as lacunae, which house mature osteocytes. The lacunae are interconnected by tiny channels called canaliculi that allow for the exchange of nutrients and wastes between osteocytes and the Haversian and Volkmann's canals.
Describe prophase 1 of meiosis
The chromatin condenses into chromosomes, the spindle apparatus forms, and the nucleoli and nuclear membrane disappear . Then, unlike mitosis, homologous chromosomes come together and intertwine in a process called synapsis. At this point, each chromosome consists of two sister chromatids so each synaptic pair contains 4 chromatids and is referred to as a tetrad (the homologous chromosomes are held together by a group of proteins called the synaptonemal complex). Chromatids of homologous chromosomes may break at the point of contact, called the chiasma (plural: chiasmata) and exchange equivalent pieces of DNA (a process called crossing over). This genetic recombination can unlink linked genes, thereby increasing the variety of genetic combinations that can be produced via gametogenesis. Note: the further apart two genes are, the more likely they are to become unlinked during crossing over.
Describe the colon
The colon is divided into the ascending, transverse, descending, and sigmoid colons. Its main function is to absorb water and salts (such as sodium chloride) from the undigested material leftover from the small intestine. The small intestine actually absorbs much more water than the colon, so the colon primarily concentrates the remaining material to form feces. Too little or too match water absorption can cause diarrhea or constipation, respectively.
A stable, differentiated cell that will NOT divide again during its lifetime would most likely be found in which of the following stages of the cell cycle? A: G1 B: G2 C: M D: S
The correct answer is A. The question asks the examinee to identify the cell cycle stage in which a stable, differentiated, nondividing cell will most likely be found. A diploid, nondividing cell is most likely in G0 or G1, in which the cell remains metabolically active but is not replicating its DNA (S) or segregating its duplicated chromosomes and dividing (M). A is the only option that lists either G0 or G1. Thus, A is the best answer.
Describe the glycerol-3-phosphate shuttle
The cytosol contains one isoform of glycerol-3-phosphate dehydrogenase which oxidizes cytosolic NADH to NAD+ while forming glycerol 3-phosphate from dihydroxyacetone phosphate (DHAP). On the outer face of the inner mitochondrial membrane, there exists another isoform of glycerol 3-phosphate dehydrogenase that is FAD-dependent. This mitochondrial FAD is the oxidizing agent and ends up being reduced to FADH2. Once reduced, FADH2 proceeds to transfer its electrons to the ETC via Complex II, thus generating 1.5 ATP for every molecule of cytosolic NADH that participates in the pathway.
Describe the two forms of the double helix
The double helix of most DNA is a right-handed helix, forming what is called B-DNA. Th helix in B-DNA makes a turn every 3.4 nm and contains about 10 bases within that span. Major and minor grooves can be identified between the interlocking strands and are often the site of protein binding. Another form of DNA is called Z-DNA for its zigzag appearance it is a left-handed helix that has a turn every 4.6nm and contains 12 bases within each turn. A high GC-content or a high salt concentration may contribute to formation of this form of DNA. No biological activity has been attributed to the formation of this form of DNA. No biological activity has been attributed to Z-DNA partly because it is unstable and difficult to research.
What is the driving force for gas exchange?
The driving force for gas exchange is the pressure differential of the gases. When it initially arrives at the alveoli, blood has a relatively low partial pressure of oxygen and a relatively high partial pressure of carbon dioxide, facilitating transfer of each down its respective concentration gradient: O2 in the alveoli flows down its partial pressure gradient from the alveoli into the pulmonary capillaries, where it can bind to hemoglobin for transport. Meanwhile, CO2 flows down its partial pressure gradient from the capillaries into the alveoli for respiration. Note: Because the gradient between the blood and air in the lungs is already present as the blood enters the lungs, no energy is required for gas transfer.
Describe the effects of peptide hormones
The effects of peptide hormones are usually rapid but short-lived because these hormones act through second messenger cascades, which are transient. Thus it is quicker to turn them on and off, compared to steroid hormones, but their effects do not last without relatively constant stimulation.
Describe the effects of steroid hormones
The effects of steroid hormones are slower but longer-lived than peptide hormones because steroid hormones participate in gene regulation, causing alteration sin the a mount of mRNA and protein present in a cell by direction action on DNA.
How is the embryo connected to the placenta?
The embryo is connected to the placenta via the umbilical cord, which consists of two arteries and one vein encased in gelatinous substance.: *The umbilical vein carries freshly oxygenated blood rich with nutrients from the placenta to the embryo. *The umbilical arteries carry deoxygenated blood and waste to the placenta for exchange.
substrate-level phosphorylation
The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.
What is one primary difference between the somatic and autonomic nervous system?
The fact that the peripheral component of the autonomic nervous system contains two neurons. Whereas a motor neuron in the somatic nervous system goes directly from the spinal cord to the muscle without synapsing.
What happens in the 2nd trimester?
The fetus begins to move, the face looks human, fingers and toes elongate, and there is TREMENDOUS growth.
Describe the first part of the PPP
The first part begins with G6P and ends with Ribulose-5-phosphate and irreversible. This part produces NADPH and involves the important rate-limiting enzyme glucose-6-phosphate dehydrogenase (G6PD). G6PD is induced by insulin because the abundance of sugar entering the cell under insulin stimulation will be shunted into both fuel utilization pathways (glycolysis and aerobic respiration) as well as fuel storage pathways (fatty acid synthesis, glycogenesis, and the PPP). The shunt is also inhibited by its product NADPH and is activated by one of its reactants, NADP+.
Describe the process of replicating DNA
The first step in the replication of DNA is actually to lay down an RNA primer. DNA cannot be synthesized de novo that is, it needs another molecule to "hook on" to. RNA, on the other hand, can be directly paired with the parent strand. Thus, primase synthesizes a short primer (roughly 10 nucleotides) in the 5' to 3' direction to start replication on each strand. These short RNA sequences are constantly being added to the lagging strand because each Okazaki fragment must start with a new primer. In contrast, the leading strand requires only one, in theory (in reality there are usually a few primers on the leading strand). DNA polymerase III (in prokaryotes) or DNA polymerases alpha, delta, and epsilon (in eukaryotes) will then begin synthesizing the daughter strands of DNA in the 5' to 3' manner. The incoming nucleotides are 5' deoxyribonucleic triphosphates: dATP, dCTP, dGTP, dTTP. As the new phosphodiester bond is made, a free pyrophosphate (PPi) is released.
What are the five histone proteins in eukaryotic cells? Which one is not part of the histone core around which DNA wraps to form chromatin?
The five histone proteins are H1, H2A, H2B, H3, and H4. H1 is the only one not in the histone core. It works to seal off the DNA as it enters and leaves the nucleosome.
What is genetic leakage?
The flow of genes between species. In some cases, individuals from different (but closely related) species can mate to produce hybrid offspring. Many hybrid offspring, such as the mule (hybrid of a male horse and a female donkey) are not able to reproduce because they have odd numbers of chromosomes.
Describe the follicular phase of the ovarian cycle
The follicular phase begins when the menstrual flow begins. GnRH secretion from the hypothalamus increases in response to decreased concentrations of estrogen and progesterone, which fall off toward the end of each cycle. The increased concentrations of GnTH cause increased secretions of both FSH and LH. These two hormones work together to develop several ovarian follicles. The follicles begin to produce estrogen which has negative feedback effects and causes the GnRH, FSH, and LH levels to level off. Estrogen stimulates regrowth of the endometrial lining, stimulating vascularization and glanduralization of the decidua.
Describe glycosidic bond formation
The formation of an alpha- or beta-glycosidic linkage is nonspecific in that the anomeric carbon of a cyclic sugar can react with any hydroxyl group on any other sugar molecule. The linkages are named for the configuration of the anomeric carbon and the numbers of the hydroxyl-containing carbons involved in the linkage. For example, in an alpha-1,6 glycosidic bond formation between two D-glucose molecules, the alpha-anomeric carbon of the first glucose (C,1) attaches to C-6 of the second glucose. The second glucose could be either an alpha or a beta-anomer. Note: in the vent that a glycosidic bond is formed between two anomeric carbons, this must be specified in the name. For example, a bond formed between the anomeric carbons of two alpha-D-glucose molecules would be an a,a-1,1 linkage.
Describe the founder effect
The founder effect is a more extreme case of genetic drift in which a small population of species finds itself in reproductive isolation from other populations as a result of natural barriers, catastrophic events, or other bottlenecks that drastically and suddenly reduce the size of the population available for breeding. Because the breeding group is small, inbreeding, or mating between two genetically related individuals, may occur in later generations.
Describe the shortening of the sarcomere in muscle contraction
The free globular heads of myosin molecules move toward and bind with the exposed sites on actin. The newly formed actin-myosin cross-bridges then allow myosin to pull on actin, which draws the thin filaments toward the M-line, resulting in shortening of the sarcomere. The process goes as follows: Myosin carrying hydrolyzed ATP is able to bind with the myosin-binding site. The release of the resulting Pi and ADP in rapid succession provides the energy for the power stroke and results in sliding of the actin filament over the myosin filament. THen, ATP binds to the myosin head, releasing it from actin. This ATP is hydrolyzed to ADP and Pi which recocks the myosin head so that it is in position to initiate another cross-bridge cycle. The repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along the thick filament, causing sequential shortening of the sarcomere.
Describe the glands of the stomach
The fundus and body contain mostly gastric glands and the antrum and pylorus contain mostly pyloric glands.
What are the support cells for neurons? Name all 4
The glial cells (neuroglia) Astrocytes, ependymal cells, microglia, and oligodendrocytes (CNS) and Schwann (PNS) cells
What is the difference between live glycogen and skeletal muscle glycogen?
The glycogen in the liver and in skeletal muscle serve two quite different roles. Liver glycogen is broken down to maintain a constant level of glucose in the blood; muscle glycogen is broken down to provide glucose to the muscle during vigorous exercise.
Describe granulocytes
The granular leukocytes or granulocytes (neutrophils, eosinophils, and basophils) are so named because they contain cytoplasmic granules that are visible by microscopy. These granules contain a variety of compounds that are toxic to invading microbes; these compounds can be released through exocytosis. Granular leukocytes are involved inflammatory reactions, allergies, pus formation, and destruction of bacteria and parasites.
What are the horizontal lines in the fischer projection? The vertical?
The horizontal lines are wedges, the vertical lines dash into the page
What occurs in disaccharide formation?
The hydroxyl group on the anomeric carbon reacts with the hydroxyl group of another sugar to form an acetal (or ketal) with a 1,2; 1,4; or 1,6 glycosidic linkage.
Describe the hypothalamus
The hypothalamus is located in the forebrain, directly above the pituitary gland and below the thalamus (hence the name hypothalamus). Because the hypothalamus and the pituitary are close to each other, the hypothalamus controls the pituitary through the paracrine release of hormones into a portal system that directly connects the two organs. That said, the release of hormones by the hypothalamus is regulated by negative feedback.
Describe the interactions between the hypothalamus and the anterior pituitary
The hypothalamus secretes compunds into the hypophyseal portal system, which is a blood vessl system that directly conencts the hypothalamis witht he anterior pituitary. Thus, hormones release form the hypothalmus travel directly to the anterior pituitary and cannot be found in appreciable concentrations in teh systemic circulation. Once hormones have been released from the hypothalamus into this portal bloodstream, they travel down the pituitary stalk and bind to receptors in the anterior pituitary, stimulatiing the release of other hormones.
What keeps the lungs from collapsing?
The indirect connection of the lings to the chest wall
Describe specification/Determination of cells on their way to specialization
The initial stage of cell specialization is specification, in which the cell is reversibly designated as a cell type. This is followed by determination, which was previously defined as the commitment of a cell to a particular function in the future. Prior to determination, the cell can become any cell type, even if it has already gone through specification. After determination, the cell is irreversibly committed to a specific lineage of cells. Note: Determination can happen during cleavage or as are the result of morphogens (specific molecules secreted from cells that make nearby cells follow a developmental pathway)
What distinguishes the inner mitochondrial membrane from other biological membranes? What is the pH gradient between the cytoplasm and the intermembrane space.
The inner mitochondrial membrane lacks cholesterol, which differentiates it from most other biological membranes. There is no pH gradient between the cytoplasm and the intermembrane space because the outer mitochondrial membrane has such high permeability to biomolecules (the proton motive force of the mitochondria is across the inner mitochondrial membrane, not the outer mitochondrial membrane).
What allows for coordinated ventricular contraction?
The intercalated discs of the myocardium which contain many gap junctions directly connecting the cytoplasm of adjacent cells
A gene encodes a protein with 150 amino acids. There is one intron of 1000 base pairs (bp), a 5'-untranslated region of 100 bp, and a 3'-untranslated region of 200 bp. In the final mRNA, about how many bases lie between the start AUG codon and final termination codon? 150 450 650 1750
The intron will not be a part of the final, processed mRNA, and the untranslated regions of the mRNA will not be turned into amino acids. Translation will begin with 1 codon (which will be AUG). Because there are 150 amino acids, we can surmise that there will be 151 codons. Each codon will use 3 nucleotides, so 150 x 3 = 450 because codon 151 will be the stop codon.
What is pI?
The isoelectric point. It is the pH at which the molecule is electrically neutral. It can be calculated in three ways. For amino acids with uncharged sidechains: pI= (pKa, NH3+ group + pKa COOH group)/ 2 For amino acids with acidic sidechains: pI= (pKa, R group + pKa COOH group)/ 2 This occurs because the proton is first lost from its main carboxyl group and then from the sidechain (acids lose protons before bases) For amino acids with basic sidechains: pI= (pKa, NH3+ group + pKa, R group)/ 2 This is because it will not become negative vs neutral until both amino groups get deprotonated
What is the lagging strand and what's the issue with it?
The lagging strand is the strand that is copied in a direction opposite the direction of the replication fork. On this side of the replication fork, the parental strand has 5' to 3' polarity. DNA polymerase cannot simply read and synthesize on this stand. Because DNA polymerase can only synthesize in the 5' to 3' direction from a 3' to 5' template, small strands called Okazaki fragments are produced. As the replication fork continues to move forward, it clears additional space that DNA polymerase must fill in. Each time DNA polymerase completes an Okazaki fragment, it turns around to find another gap that needs to be filled in.
What is Mendel's second law?
The law of independent assortment: it states that the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes
Describe recombination frequency
The likelihood that two alleles are separated from each other during ccrossing over is called teh recombiantion frequeenyc. It is roughly proportional to the distnace between genes on the chromosome. We can also describe the strength of llinkage between genes based on the recombination frequency: tightly linked genes have recombination frequencoes close to 0 percent; weakly linked genes have recombination frequencies approaching 50%, as expecte dfrom independent assortment.
Describe the liver
The liver is located in the upper right quadrant of the abdomen. It not only produces bile but also receives all blood draining from the abdominal portion of the digestive tract through the hepatic portal vein. This nutrient-rich blood can be processed by the liver before draining into the inferior vena cava on its way to the right side of the heart. For example, the liver takes up excess sugar to create glycogen, the storage form of glucose, and stores fats as triacylglycerols. The liver can also reverse these processes producing glucose for the rest of the body through glycogenolysis and gluconeogenesis and mobilizing fats in lipoproteins. The liver detoxifies both endogenous compounds (those made in the body) and exogenous compounds (those brought in from the environment). For example, the liver converts ammonia, a toxic waste product of amino acid metabolism, into urea, which can be excreted by the kidneys. The liver also detoxifies and metabolizes alcohol and medications. Note: some drugs actually require activation by the enzymes of the liver. In addition, some drugs cannot be taken orally because modification of these drugs by the liver renders them inactive.
What happens in the 1st trimester?
The major organs of the embryo begin to develop, the heart beats, the skeleton hardens to bone, the brain fully develops, and then as a result the embryo becomes known as a fetus. This can be summed up as "organogenesis"
Describe the effects of amino-acid derivative hormones
The mechanism of action of amino acid-derivative hormones should be memorized because it is so unpredictable: Epinephrine and norepinephrine have extremely fast onset but are short-lived, like peptide hormones -- think of an adrenaline rush. Thus these hormones bind to G-protein coupled receptors to do a signal cascade. Thyroxine and triiodothyronine (T3) have slower onset but a longer duration, like steroid hormones--they regulate metabolic rate over a long period of time. Thus these hormones bind intracellularly.
When concentrated urine is being produced, in win what region of the kidney will the glomerular filtrate reach its highest concentration?
The medullary portion of the collecting duct
Binary fission
The method of bacterial reproduction. It is a form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size--assuming no mutation or genetic recombination all bacteria in the colony will be the same. In binary fission, the new copy of DNA is attached to the cell membrane and the cell then splits in half in between the two copies of DNA.
Describe the modern synthesis model
The modern synthesis model takes natural selection and explains that selection is specific for alleles, which are passed on to future generations through formation of gametes; the alleles for these favorable traits arise from mutations.
What happens at the end of translation?
The nascent polypeptide chain is subjected to posttranslational modifications before it will become a functioning protein, similar to how hnRNA is modified prior to being released from the nucleus. One essential step for the final synthesis of protein is proper folding. There is a specialized class of proteins called chaperones, the main function of which is to assist in the protein folding process. Many proteins are also modified by cleavage events. A common example of this is insulin, which needs to be cleaved from a larger, inactive peptide to achieve its active form. In peptides with signal sequences, the signal sequence must be cleaved if the protein is to enter the organelle and accomplish its function. Other biomolecules may be added to the peptide via the following processes: phosphorylation (done to active or inactivate proteins), carboxylation (addition of carboxylic acid usually serves as calcium-binding sites), glycosylation (done as proteins pass through the ER and Golgi apparatus to determine cellular destination), and prenylation (addition of lipid groups to certain membrane-bound enzymes)
Other than taking in air what do the mouth and nose offer as far as respiration
The nose and mouth serve several important roles in breathing by removing dirt and particulate matter from the air and warming and humidifying it before it reaches the lungs
Describe prophase 2 of meiosis
The nuclear envelope dissolves, nucleoli disappear, the centrioles migrate to opposite poles, and the spindle apparatus begins to form.
Describe the omega numbering system
The omega numbering system is used for unsaturated fatty acids. The ω designation describes the position of the last double bond relative to the end of the chain and identifies the major precursor fatty acid. For example, linoleic acid (18:2 cis, cis- 9, 12) is the precursor of the ω-6 family, which includes arachidonic acid. α-linolenic acid (18:3 all-cis9,12,15) is the primary precursor of the ω-3 family. Note: double bonds in fatty acids are generally in the cis configuration
If an enzyme is saturated, how do we increase vmax?
The only way is by adding more enzyme
Describe the ovaries
The ovaries produce estrogen and progesterone. Each consists of thousands of follicles, whi are multilayered sacs that contain, nourish, and protect immature ova (eggs).
How is material from the spermatid and ovum divied into the zygote?
The ovum gives the zygote half its DNA, all of its cytoplasm, organelles, and RNA, while the spermatocytes only contribute half of their DNA. Thus, upon completion of meiosis II, the haploid pronuclei of the sperm and the ovum join, creating a diploid zygote.
Describe the pancreas
The pancreas has both exocrine and endocrine functions. Exocrine tissues secrete substances directly into ducts the pancreas produces a number of digestive enzymes. From an endocrine standpoint, small clusters of hormone-producing cells are grouped together into islets of Langerhans throughout the pancreas. The islets contain three distinct types of cells: alpha. beta, and delta. Each cell type secretes a different hormone alpha-cells secrete glucagon, beta-cells secrete insulin, and delta-cells secrete somatostatin, You BETA be making insulin in there
Describe the function of the pancreas
The pancreas serves two quite different roles in the body, reflecting its exocrine and endocrine functions: The endocrine functions include the release of insulin, glucagon, and somatostatin -- peptide hormones necessary for the maintenance of proper blood sugar levels. The hormonal function of the pancreas is limited to cells residing in the islets of Langerhans scattered throughout the organ. The bulk of the pancreas, however, is made of exocrine cells called acinar cells that produce pancreatic juices--pancreatic juices are bicarbonate-rich alkaline secretions containing many digestive enzymes that wor on all three classes of biomolecules.
Describe the pancreatic peptidases
The pancreatic peptidases (trypsinogen, chymotrypsinogen, and carboxypeptidases A and B) are leased in their zymogen form, but once activated are responsible for protein digestion. --enteropeptidase, produced by the duodenum, is the master switch. It converts trypsinogen to trypsin which can then activate the other zymogens, and also activates procarboxypeptidases A and B.
Describe the parathyroid glands
The parathyroid glands are four small pea-sized structures that sit on the posterior surface of the thyroid. The hormone produced by the parathyroid glands is aptly named parathyroid hormone (PTH). PTH serves as an antagonistic hormone to calcitonin, raising blood calcium levels; specifically, it decreases the excretion of calcium by the kidneys. increases absorption of calcium in the gut (via activation of vitamin D), and increases bone resorption, thereby freeing up calcium. When it comes to calcium, PTH is subject to feedback inhibition. As levels of plasma calcium rise, PTH secretion is decreased. PTH also promotes phosphorous homeostasis by increasing the resorption of phosphate from bone and reducing reabsorption of phosphate in the kidney (thus promoting its excretion in urine). PTH also activates vitamin D which is needed for the absorption of calcium and phosphate in the gut. The overall effect of parathyroid hormone, therefore, is a significant increase in blood calcium levels with little effect on phosphate (the absorption of phosphate in the gut and its excretion in the kidney somewhat cancel each other out).
Describe the pentose phosphate pathway
The pentose phosphate pathway occurs in the cytoplasm of all cells, where it serves two major functions: production of NADPH and serving as a source of ribose-5-phosphate for nucleotide synthesis.
What's the difference between the pharynx and the larynx?
The pharynx resides behind the nasal cavity and at the back of the mouth; it is a common pathway for both air destined for the lungs and food destined for the esophagus. In contrast, the larynx lies below the pharynx and is only a pathway for air.
Describe the pineal gland
The pineal gland is located deep within the brain, where it secretes the hormone melatonin. The precise mechanism of this hormone is unclear, although it has been demonstrated to be involved in circadian rhythms. Blood levels of melatonin are at least partially responsible for the sensation of sleepiness. The pineal gland receives projection directly from the retina, but is not involved in vision; it is hypothesized that the pineal gland responds to decreases in light intensity by releasing melatonin.
What is pka?
The pka of a group is the pH at which on average half of the molecules of that species are deprotonated, where [protonated version] = [deprotonated version] or [HA-]= [A-]. Note: when [HA-] = [A-], pH =pka and the solution will be acting as a buffer (indicated by the blue boxes in the picture)
What type of organ is the placenta?
The placenta is considered an endocrine organ because it produces progesterone, estrogen, and hCG.
Describe polymerase chain reaction
The polymerase chain reaction is an automated process that can produce millions of copies of a DNA sequence without amplifying the DNA in bacteria. PCR is used to identify criminal suspects, familial relationships, and disease-causing bacteria and viruses. Knowing the sequences that flank the DNA allows for the amplification of the sequence in between. A PCR reaction requires primers that are complementary to the DNA that flanks the region of interest, nucleotides (dATP, dCTP, dGTP, and dTTP), and DNA polymerase. The primer has high GC content, as the additional hydrogen bonds between G and C confer stability. The reaction also needs heat to cause the DNA double helix to melt apart (denature). Unfortunately, the DNA polymerase found in the human body does not work at high temperatures. Thus, the DNA polymerase from Thermus aquaticus, a bacteria that thrives in the hot springs of Yellowstone National Park, is used instead. During PCR, the DNA of interest is denatured, replicated, and then cooled to allow reannealing of the daughter strands with the parent strands. This process is repeated several times, doubling the amount of DNA with each cycle, until enough copies of the DNA sequence are available for further testing.
Describe the interactions between the hypothalamus and the posterior pituitary
The posterior pituitary doe NOT receive tropic hormones through the hypophyseal portal system. Rather neurons in the hypothalamus send their axons down the pituitary stalk directly into the posterior pituitary, which can then release oxytocin and antidiuretic hormone (ADH).
Describe how active muscle gets energy
The primary fuel used to support muscle contraction depends on the magnitude and duration of exercise as well as the major fibers involved. A very short-lived source of energy (2-7 seconds) comes from creatine phosphate, which transfers a phosphate group to ADP to form ATP. Skeletal muscle has stores of both glycogen and some triacylglycerols. Blood glucose and free fatty acids may also be used. Short bursts of high-intensity exercise are also supported by anaerobic glycolysis drawing on stored muscle glycogen. During moderately high-intensity, continuous exercise, oxidation of glucose and fatty acids are both important, but after 1 to 3 hours of continuous exercise at this level, muscle glycogen stores become depleted, and the intensity of exercise declines to a rate that can be supported by oxidation of fatty acids.
What is the primary structure of a protein?
The primary structure is the linear arrangement of covalently bound amino acids. It is stabilized by peptide bonds between adjacent amino acids.
oxidative phosphorylation
The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.
Describe the pyloric glands of the stomach
The pyloric glands contain G-cells that secrete gastrin, a peptide hormone. Gastrin induces the parietal cells in the stomach to produce more HCl and signals the stomach to contract, mixing its contents. The digestion of solid food in the stomach results in an acidic, semifluid mixture called chyme. The combined mechanical and chemical digestive activities of the stomach result in a significant increase in the surface area of the now unrecognizable food particles, so when the chyme reaches the small intestine, the absorption of nutrients from it can be maximized.
How much ATP does the pyruvate dehydrogenase complex make?
The pyruvate dehydrogenase complex creates 1 NADH which can be transformed into 2.5 ATP
Mutarotation
The rapid interconversion between different anomers of a sugar: Exposing hemiacetal rings to water will cause them to spontaneously cycle between the open and closed forms. Because the substituents on the single bond between C-1 and C-2 can rotate freely, either the alpha- or beta-anomer can be formed. Mutarotation results in a mixture that contains both alpha- and beta-anomers at equilibrium concentrations. That said, in solution, the alpha-anomeric configuration is less favored because the hydroxyl group of the anomeric carbon is axial, adding to the steric strain of the molecule--it drags it down.
What are the reactants of the pyruvate dehydrogenase complex? What are the products?
The reactants are pyruvate, NAD+, and COA and the products are acetyl-CoA, NADH, and CO2.
If H+ is an acid and HCO3- is a base, then why doesn't increasing both of them yield a constant pH?
The reason is hat H+ is a strong acid, while HCO3- is a weak base. This combination will shift the pH of the solution toward the acidic range.
Describe the rectum
The rectum serves as a storage site for feces, which consists of indigestible material, water, bacteria, and certain digestive secretions that are not reabsorbed.
What does it mean to have blood type A?
The red blood cells contain A antigens and the person has anti-B antibodies. Thus, they can donate blood to people who have A or AB genotypes, but they can only receive blood from people with A or O genotypes.
What does it mean to have blood type AB?
The red blood cells contain AB antigens and the person has no blood antibodies. Thus, they can only donate blood to people who have AB genotypes, but they can receive blood from people with A, B, AB or O genotypes. They are the universal receivers!
What does it mean to have blood type B?
The red blood cells contain B antigens and the person has anti-A antibodies. Thus, they can donate blood to people who have B or AB genotypes, but they can only receive blood from people with B or O genotypes.
What does it mean to have blood type O?
The red blood cells contain no antigens but the person has anti-A antibodies and anti-B antibodies. Thus, they can donate blood to people who have A, B, O, or AB genotypes (they are the universal donor!), but they can only receive blood from people with O genotypes.
What causes the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary? What does it then act on?
The release of ACTH is stimulated by corticotropin-releasing factor (CRF) from the hypothalamus. Once ACTH is released, it then goes to act on the adrenal cortex and causes release of glucocorticoids (cortisol and cortisone). *Hormones that come from the hypothalamus have "releasing" in the name
What causes release of FSH from the anterior pituitary? What does it then act on?
The release of FSH is stimulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. Once FSH is released, it then goes to act on the gonads (testes and ovaries) *Hormones that come from the hypothalamus have "releasing" in the name
What causes the release of growth hormone (GH) from the anterior pituitary?
The release of GH is stimulated by growth hormone-releasing hormone (GHRH) from the hypothalamus. *Hormones that come from the hypothalamus have "releasing" in the name
What causes release of LH from the anterior pituitary? What does it then act on?
The release of LH is stimulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. Once LH is released, it then goes to act on the gonads (testes and ovaries) *Hormones that come from the hypothalamus have "releasing" in the name
What causes the release of TSH from the anterior pituitary? What does it then act on?
The release of TSH is stimulated by thyroid-releasing hormone (TRH). Once TSH is released, it then goes to act on the thyroid and causes the release of T3 (triiodothyronine) and T4 (thyroxine). *Hormones that come from the hypothalamus have "releasing" in the name
Describe pancreatic juices
The release of these juices occurs in the duodenum and is stimulated by CCK. Pancreatic juices are a complex mixture of several enzymes in a bicarbonate-rich alkaline solution. This bicarbonate helps to neutralize acidic chyme, as well as provide an ideal working environment for the digestive enzymes, which are most active around pH 8.. Pancreatic juices contain enzymes that can digest all three types of nutrients: carbohydrates, fats, and proteins. These enzymes are: *Pancreatic amylase- which breaks down large polysaccharides into small disaccharides and is therefore responsible for carbohydrate digestion. *The pancreatic peptidases (trypsinogen, chymotrypsinogen, and carboxypeptidases A and B) are leased in their zymogen form, but once activated are responsible for protein digestion. --enteropeptidase, produced by the duodenum, is the master switch. It converts trypsinogen to trypsin which can then activate the other zymogens, and also activates procarboxypeptidases A and B. *Pancreatic lipase- which is capable of breaking down fats into free fatty acids and glycerol Pancreatic juices are transferred to the duodenum via a duct system that runs along the middle of the pancreas. Like all exocrine cells, acinar cells secrete their products into ducts. These ducts then empty into the duodenum through the major and minor duodenal papillae.
Long term or heavy smokers damage the cilia of their respiratory epithelia. Which of the following is NOT likely to result from this damage? *Increased infection by pathogenic organisms *Increased obstructive lung disease *Decreased alveolar gas exchange *decreased cough reflex
The respiratory cilia are responsible for moving mucus and trapped particles from the lungs and upper respiratory tract to the pharynx for disposal by swallowing. In this way, respiratory cilia also protect against infection by removing bacteria and viruses. If the mucus is not transported, it ca cause obstruction of the respiratory pathways, as seen in COPD. Nonmotile cilia in the respiratory epithelia are responsible for the cough reflex. As they are damaged smokers cough less, contributing to the obstructive disease. Alveoli do not have cilia, thus changes in alveolar gas exchange result from other mechanisms.
Describe the sides of the heart
The right side of the heart accepts deoxygenated blood returning from the body and moves it to the lungs by way of the pulmonary arteries -- this makes up the pulmonary circulation. The left side of the heart receives oxygenated blood from the lungs by way of the pulmonary veins and forces it out to the body through the aorta -- this makes up the systemic circulation
As glucose, a reducing sugar, is oxidized during Fehling's reaction, how is the equilibrium between hemiacetal D-glucose and linear D-glucose shifted?
The ring and linear forms f glucose are in equilibrium initially. However, only the linear form of glucose can undergo oxidation. Hence, as the Fehling's reaction progresses, more and more of the linear form of glucose gets consumed, causing the equilibrium reaction between the linear and ring form of glucose to shift towards linear glucose. There is a shift favoring the replacement of the linear form of glucose.
What is a sarcolemma?
The sarcolemma is the cell membrane of a myocyte. It is capable of propagating an action potential and can distribute the action potential to all sarcomeres in a muscle using a system of transverse tubules (T-tubules) that are oriented perpendicularly to the myofibrils.
Describe thrombocytes
Theombocytes or platelets are cell fragments or shards relseased from cells in bone marrow known as megakaryotcytes. Their function is to assist in blood clotting and they are present in high concentrations.
Describe the sarcomere
The sarcomere is the basic contractile unit of skeletal muscle. Sarcomeres are made up of thick and thin filaments. The thick filaments are organized bundles of myosin, whereas the thin filaments are made up of actin along with other proteins: troponin and tropomyosin. These proteins help to regulate the interaction between the actin and myosin filaments. Another protein, titin, acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of the muscle.
Describe the second part of the PPP
The second part of the pathway, beginning with ribulose 5-phosphate (R5P), represents a series of reversible reactions that produce an equilibrated pool of sugars for biosynthesis, including ribose-5-phosphate for nucleotide synthesis. Because fructose 6-phosphate and glyceraldehyde 3-phosphate are among the sugars produced, intermediates can feed back into glycolysis; conversely, pentoses can be made from glycolytic intermediates without going through the G6PD reaction. These interconversions are primarily accomplished by the enzymes transketolase and transaldolase.
What is the SRY gene?
The sex determining region of the Y chromosome. The SRY gene codes for a transcription factor that initiates testis differentiation and thus the formation of male gonads.
Describe the sliding clamp
The sliding clamp is a trimer formed by DNA polymerases delta and epsilon and PCNA protein. The clamp helps to strengthen the interaction between DNA polymerases and the the template strand.
Describe the small intestine
The small intestine consists of three segments: the duodenum, the jejunum, and the ileum. The duodenum is responsible for the majority of chemical digestion and has some minor involvement in absorption. However, most of the absorption in the small intestine takes place in the jejunum and ileum/.
Describe the structure of the small intestine
The small intestine is lined with villi, which are small, fingerlike projections from the epithelial lining. Each villus has many microvilli, drastically increasing the surface area available for absorption. In addition, at the middle of each villus, there is a capillary bed for the absorption of water-soluble nutrients and a lacteal, a lymphatic channel that takes up fats for transport into the lymphatic system.
Describe initiation of translation
The small ribosomal subunit binds to the mRNA.: In prokaryotes, the small subunit binds to the Shine-Dalgarno sequence in the 5' untranslated region of the mRNA. In eukaryotes, the small subunit binds to the 5' cap structure. The charged initiator tRNA binds to the AUG start codon through base pairing with its anti-codon within the P site of the ribosome: The initial amino acid in prokaryotes is N-formylmethionine (fMEt); while in eukaryotes it's methionine. The large subunit then binds to the small subunit, forming the completed initiation complex. Note: This process is assisted by initiation factors (IF) that are not permanently associated with the ribosome.
Describe the synapse process of the autonomic neurons
The soma of the preganglionic neuron is in the CNS, and its axon travels to a ganglion in the PNS. Here it synapses on the cell body of the postganglionic neuron, which then stimulates the target tissue.
What gives compact bone its strength?
The strength of compact bone come from the bone matrix, which has both organic and inorganic components. The organic components include collagen, glycoproteins, and other peptides. The inorganic components include calcium, phosphate, and hydroxide ions, which harden together to form hydroxyapatite crystals. Minerals such as sodium, magnesium, and potassium are also stored in bone.
What is the rate limiting step of cholesterol synthesis?
The synthesis of mevalonic acid in the smooth ER is the rate-limiting step in cholesterol synthesis and is catalyzed by HMG CoA reductase.
What are the targets of insulin?
The three major target tissues for insulin are the lover, muscle, and adipose tissue. Insulin promotes glycogen synthesis in the liver and muscle. After the glycogen stores are filled, the liver converts excess glucose to fatty acids and triacylglycerols. Insulin promotes triacylglycerol synthesis in adipose tissue and protein synthesis in muscle, as well as glucose entry into both tissues. After a meal, most of the energy needs of the liver are met by the oxidation of excess amino acids.
Describe the thymus
The thymus, located directly behind the sternum, releases thymosin, which is important for proper T-cell development and differentiation. The thymus atrophies by adulthood, and thymosin levels drop accordingly.
Describe the thyroid
The thyroid is controlled by TSH from the anterior pituitary. The thyroid is on the front surface of the trachea; it can be palpitated as an organ heart the base of the neck that moves up and down with swallowing. The thyroid has two major functions: *setting basal metabolic rate: it mediates this by releasing T3 (triiodothyronine) and T4 (thyroxine), while it carries out the second effect through the release of calcitonin. *Promoting calcium homeostasis
What type of operon is the trp operon? The lac operon?
The trp operon is a negative repressible operon The trp operon is a negative inducible operon
Describe release of hormones by the posterior pituitary
The two hormones released from the posterior pituitary (oxytocin and ADH) are actually synthesized in the hypothalamus and simply released from the posterior gland. The posterior pituitary does not synthesize any hormones itself.
What are the two major metabolic products of the pentose phosphate pathway?
The two metabolic products of the PPP are ribose 5-phosphate and NADPH.
What happens during denaturation of DNA?
The two strand separate but the phosphate backbone remains unbroken
What is the function of the variable and constant regions of an antibody?
The variable regions of both the heavy and light chains are involved in antigen binding, while the constant region of the heavy chain is involved in cellular recognition and the constant region of the light chain binds tightly to the constant region of the heavy chain; neither constant region is normally involved in antigen binding.
How is CO2 transported by blood?
The vast majority of CO₂ exists in the blood as the bicarbonate ion (HCO₃-). When CO₂ enters a red blood cell, it encounters the enzyme carbonic anhydrase, which catalyzes the combination reaction between carbon dioxide and water to form carbonic acid (H₂CO₃ ). Carbonic acid, a weak acid, will dissociate into a proton and the bicarbonate anion. The hydrogen ion (proton) and the bicarbonate ion both have high solubilities in water, making them a more effective method of transporting metabolic waste products to the lungs for excretion. Upon reaching the alveolar capillaries in the lungs, the same reactions that led to the formation of the proton and bicarbonate anion can be reversed, allowing us to breather out carbon dioxide. CO₂ (g) + H₂O (l) ↔H₂CO₃ (aq) ↔ H+(aq) + HCO₃-(aq)
What is the mathematical relationship between vital capacity (VC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and Tidal Volume?
The vital capacity is everything except the residual volume so: VC= IRV + ERV + TV
What is the collective term for the external female anatomy?
The vulva
Describe glycosphingolipids
These are sphingolipids with head groups composed of sugars bonded by glycosidic linkages, they are considered glycolipids. These molecules are not phospholipids because they contain no phosphodiester linkage. Glycosphingolipids are found mainly on the outer surface of the plasma membrane and can be further classified as cerebrosides or globosides: cerebrosides have a single sugar whereas globosides have two or more. These molecules are also referred to as neutral glycolipids because they have no net charge at physiological pH.
Describe enhancers
These are used in control of gene expression in eukaryotes. Response elements outside the normal promoter regions can be recognized by specific transcription factors to enhance transcription levels. Several response elements may be grouped together to form an enhancer, which allows for the control of one gene's expression by multiple signals. Enhancer regions in the DNA can be up to 1---- base pairs from the gene they regulate and can even be located within an intron, or non-coding region, of the gene. They differ from upstream promoter elements in their locations because upstream promoter elements must be within 25 bases of the start of a gene. By utilizing enhancer regions, genes have an increased likelihood to be amplified because of the variety of signals that can increase transcription levels. Note: The large distance between the enhancer and the promoter regions for a given gene means that DNA often must bend into a hairpin loop to bring these elements together spatially.
Describe transcription factors
These are used in control of gene expression in eukaryotes. Transcription factors are transcription-activating proteins that search the DNA looking for specific DNA binding motifs. Transcription factors tend to have two recognizable domains: a DNA-binding domain and an activation domain *The DNA-binding domain binds to a specific nucleotide sequence in the promoter region or to a DNA response element (a sequence of DNA that binds only to specific transcription factors) to help in the recruitment of transcriptional machinery. *The activation domain allows for the binding of several transcription factors and other important regulatory proteins, such as RNA polymerase and histone acetylases, which function in the remodeling of the chromatin structure
Describe the cortical sex hormones
These hormones are made by the adrenal glands. They include androgens and estrogens. Because the testes already secrete large quantities of androgens, adrenal testosterone plays a relatively small role in male physiology. But because the ovaries secrete far smaller amounts of androgens, females are much more sensitive to disorders of cortical sex hormone production. For example, certain enzyme deficiencies in the synthetic pathways of other adrenal cortex hormones result in excess androgen production in the adrenal cortex. Such a deficiency would result in excess androgen production in no obvious phenotypic effects in a male fetus; however, a genotypic female may be born with ambiguous or masculinized genitalia due to the presence of excess cortical sex hormones. Note: Males can be affected by similar disorders if they lead to excessive production of estrogens.
Describe ependymal cells
They are glial cells that line the ventricles of the brain and produce cerebrospinal fluid, which physically supports the brain and serves as a shock absorber.
Describe astrocytes
They are glial cells that nourish neurons and form the blood-brain barrier, which controls the transmission of solutes from the bloodstream into nervous tissue.
Describe integral proteins
They are molecules embedded in the lipid bilayer. They have an association with the interior of the plasma membrane, which is usually assisted by one or more membrane-associated domains that are partially hydrophobic. Those that extend through the entire thickness of the membrane are called transmembrane proteins.
Describe microglia
They are phagocytic glial cells that ingest and breakdown waste products and pathogens in the central nervous system
Describe prokaryotes
They are single-celled organisms that have no nucleus, just a nucleoid structure (which does not have a nuclear envelope). They also have no membrane-bound organelles. They do, however, have a cell wall. There are two types of cell walls a prokaryote can have: gram-negative or gram-positive
In terms of membranes, what do eukaryotes and gram negative bacteria have in common?
They both have a membrane on the outer surface of the cell.
How can tears and saliva provide immune defense?
They contain an antibacterial compound known lysozyme.
What is true about carbohydrate enantiomers?
They differ at ALL chiral carbons.
If a strand of RNA contained 15% cytosine, 15% adenine, 35% guanine, and 35% uracil, would this violate Chargaff's rules? Why or why not?
This does not violate Chargaff's rules. RNA is single-stranded, and thus the complementarity seen in DNA does not hold true. For single-stranded RNA, %C does not necessarily equal %G, %A does not necessarily equal %U.
What happens once lipid diffused into an enterocyte during digestion?
They enter the SMOOTH ENDOPLASMIC RETICULUM and are re-esterified with FFAs back into TGs, PLs, and cholesterol esters. These compounds then are packed into chylomicrons and then exocytose out of the enterocyte and enter the lymph lacteals. They then drain into the bloodstream via the thoracic duct (the chylomicron is too big to go through capillaries), enter the systemic circulation, and reach the liver and diffuse in. Note that more water-soluble short-fatty acids can be absorbed by simple diffusion directly into the bloodstream. *We ate these compounds, digested them so that we could absorb them, and then built them back up. They will be processed into lipoproteins such as VLDL, LDL, and HDL.
How do transmembrane proteins enter the endomembrane system?
They enter the endomembrane system by docking at the rough ER. This is facilitated by using a signal sequence.
Why can monosaccharides take on cyclic structures?
They have both a hydroxyl group, which can serve as a nucleophile, and a carbonyl group, which is the most common electrophile on the MCAt
What is the role of sertoli cells?
They secrete fluid that bathes and nourishes the developing sperm. Thus they provide protection, nutrition, and support to developing sperm
What is the role of leydig cells?
They secrete testosterone and other male sex hormones (androgens)
What is the function of suppressor (regulatory) T -cells (Treg)?
They tone down the immune response after infection and promote self-tolerance
Describe competitive inhibition
This can be overcome by adding more substrate so that the substrate to inhibitor ratio is higher. Adding a competitive inhibitor does not alter Vmax because if enough substrate is added, it will out-compete the inhibitor and be able to run the reaction at max velocity. A competitive inhibitor however does increase km because we had to add more substrate to overcome.
Where does transcription occur? Translation?
Transcription takes place in the nucleus while translation takes place in the cytosol
Describe the peiphyseal growth plate
This is a cartilaginous structure and the site of longitudinal bone growth. Prior to adulthood, the epiphyseal growth plate is filled with mitotic cells that contribute to growth; during puberty, these epiphyseal plates close and vertical growth is halted.
Describe interferons
This is a part of the nonspecific immune response. To protect against viruses, cells that have been infected with viruses produce interferons, proteins that prevent viral replication and dispersion. Interferons cause nearby cells to decrease the production of both viral and cellular proteins. They also decrease the permeability of these cells, making it harder for a virus to infect them. In addition, interferons upregulate MHC class I and class II molecules, resulting in increased antigen presentation and better detection of the infected cells by the immune system. Interferons are responsible for many "flu-like" symptoms that occur during viral infection, include malaise, tiredness, muscle soreness, ad fever.
Describe the complement system
This is a part of the nonspecific immune response. The complement system consists of a number of proteins in the blood that act as a nonspecific defense against bacteria. Complement can be activated through a classical pathway (which requires the binding of an antibody to a pathogen) or an alternative pathway (which does not require antibodies). The complement proteins punch holes in the cell walls of bacteria, making them osmotically unstable. Despite the association with antibodies, complement system is considered a nonspecific defense because it cannot be modified to target a specific organism over others.
How are RNA primers removed after DNA replication?
This is accomplished by the enzyme DNA polymerase I (in prokaryotes) or RNase H (in eukaryotes). Then, DNA polymerase I (in prokaryotes) or DNA polymerase delta (in eukaryotes) adds DNA nucleotides where the RNA primer had been. DNA ligase seals the ends of the DNA molecules together, creating one continuous strand of DNA.
Describe G1 phase of the cell cycle
This is known as the pre synthetic gap. During the G1 stage, cells create organelles for energy and protein production while also increasing their size. Passage into the S (synthesis) stage is generated by a restriction point, here the cell is checked to see if it contains the proper complement of DNA
Describe conjugation
This is the bacterial form of mating (conjugate). It involves two cells forming a conjugation bridge between them that facilitates the transfer of genetic material. The material moves unidirectionally from donor male (+) to donor female (-). The bridge is made from sex pili on the donor male. To form the pilus, bacteria must contain plasmids known as sex factors. This gets replicated and donated from the F+ cell to the F- cell making the F- cell F+. Other plasmids can be passed along with it.
Describe the endoderm
This is the innermost layer of the primary germ layers. It forms the epithelial linings of the digestive and respiratory tracts, including the lungs. The pancreas, thyroid, bladder, and distal urinary tracts, as well as parts of the liver are also derived from the endoderm.
Describe the mesoderm
This is the middle layer of the primary germ layers. It develops into several different systems including the musculoskeletal, circulatory, and most of the excretory systems. Mesoderm also gives rise to the gonads as well as the muscular and connective tissue layers of the digestive and respiratory systems and the adrenal cortex.
Describe the ectoderm
This is the outermost layer of the primary germ layer. It gives rise to the integument, including the epidermis, hair, nails, and the epithelia of the nose, mouth, and lower anal canal. The lens of the eye, nervous system (including the adrenal medulla which comes from the nervous system), and inner ear are also derived from the ectoderm.
Describe the S phase of the cell cycle
This is the phase where the synthesis of DNA takes place. During the S stage, the cell replicates its genetic material so that each daughter cell will have identical copies. After replication, each chromosome consists of 2 sister chromatids that are bound together at the centromere. Note that the ploidy of the cell does not exchange even though the number of chromatids has doubled. Humans in this stage still only have 46 chromosomes, even though 92 chromatids are present. Cells entering G2 thus have twice as much DNA as cells in G1. Also, each chromatid is composed of a complete double-stranded molecule of DNA.
Describe the HPA axis
This is the stress response: The hypothalamus makes the hormone CRF which gets into the anterior pituitary which will make ACTH which will then affect the zonae fasiculata and reticularis in the adrenal gland. The fasiculata will release cortisol and the reticularis will release adrenal adrinogens such as EPi and Norepi. The cortisol will lead to increased energy and decreased inflammation while EPi and Norepi will lead to increased HR, respiration, blood flow, and muscle strength. Note: The adrenal gland is also being activated by the sympathetic nervous system which gets activated by CRH
What happens in telophase?
This is thought of as the reverse of prophase: The spindle apparatus disappears. A nuclear membrane reforms around each set of chromosomes and the nucleoli reappear. The chromosomes uncoil resuming their interphase form.
Describe DNA methylation
This is used in control of gene expression in eukaryotes. DNA methylation is involved chromatin remodeling and regulation of gene expression levels in the cell. SNA methylases add methyl groups to cytosine and adenine nucleotides; methylation of genes is often linked with the silencing of gene expression. During development, methylation plays an important role in silencing genes that no longer need to be activated. Heterochromatin regions of the DNA are much more heavily methylated, hindering access of the transcriptional machinery to the DNA.
Describe histone acetylation
This is used in control of gene expression in eukaryotes. Transcription factors that bind to the DNA can recruit other coactivators such as histone acetylases. These proteins are involved in chromatin remodeling because they acetylate lysine residues found in the amino-terminal tail of histone proteins. Acetylation of histone proteins decreases the positive charge on lysine residues and weakens the interaction of the histone with DNA, resulting in an open chromatin conformation that allows for easier access of the transcriptional machinery to the DNA. Thus, specific patterns of histone acetylation can lead to increased gene expression levels. On the other hand, gene silencing can occur just as easily with chromatin remodeling. Histone deacetylases are proteins that function to remove acetyl groups from histones, which results in a closed chromatin conformation and an overall decrease in gene expression levels in the cell.
Describe the variable region of an antibody
This region is located at the tip of the Y. Within this region, there are specific polypeptide sequences that will bind one, and only one, specific antigenic sequence--part of the reason it takes so long to initiate the antibody response is that each B-cell undergoes hypermutation of its antigen-binding region, trying to find the best match for the antigen; only those B-cells that can bind the antigen with high affinity survive, providing a mechanism for generating specificity called clonal selection.
Draw Threonine
Thr; T
Which of the following hormones has the greatest direct effect on mitochondria? *Insulin *Glucagon *Growth Hormone *Thyroid Hormone
Thyroid hormone Thyroid hormone passes through the cell membrane ad the mitochondrial membrane to exert a portion of its influence on metabolism. The other hormones listed act through second messengers or by modifying the concentration of substrates, not via direct action.
Describe thyroid hormone activity
Thyroid hormone activity is largely permissive. IN other words, thyroid hormone levels are kept more or less constant, rather than undulating with changes in metabolic state. Thyroid hormones increase the basal metabolic rate, as evidenced by increased O2 consumption and heat production when they are secreted. Note: the increase in metabolic rate by a dose of thyroxine (T4) occurs after a latency of several hours but may last for several days, while triiodothyronine (T3) produces a more rapid increase in metabolic rate and has a shorter duration of activity. Thyroid hormones have their primary effects on lipid and carbohydrate metabolism. They accelerate cholesterol clearance from the plasma and increase the rate of glucose absorption from the small intestine. Epinephrine requires thyroid hormones to have a significant metabolic effect.
Describe tight junctions
Tight junctions prevent solutes from leaking into the space between cells via a paracellular route. Tight junctions are found in epithelial cells and function as a physical link between the cells as they form a single layer of tissue. Tight junctions can limit permeability enough to create a transepithelial voltage difference based on differing concentrations of ions on either side of the epithelium. To be effective, tight junctions must form a continuous band around the cell; otherwise fluid could leak through spaces between tight junctions
Epithelial tissue
Tissue that covers outside of the body and lines organs and cavities.
What is the role of titin?
Titan acts as a spring and anchors the actin and myosin filaments together, preventing excessive stretching of the muscle.
What is ATP used for?
To fuel energetically unfavorable reactions or to activate or inactivate other molecules
To be an effective therapy, an antisense gene that is incorporated into a genome that contains the target gene must be:
To provide effective therapy, this antisense gene would need to be regulated in a manner similar to the manner in which the target gene is regulated so that the antisense RNA is produced at the same time that the sense mRNA is produced. This would ensure that the antisense RNA is available to bind with the sense mRNA, thereby preventing its subsequent translation.
What is the function of parietal cells?
To secrete HCl and intrinsic factor
What is the function of chief cells?
To secrete pepsinogen
What reagents are used to detect the presence of reducing sugars?
Tollen's reagent and Benedict's reagent: Tollen's reagent must be freshly prepared starting with silver nitrate (AgNO3), which is mixed with NaOH to produce silver oxide (Ag2O). Silver oxides dissolved in ammonia to produce [Ag(NH3)2]+, the actual Tollen's reagent. Tollen's reagent is reduced to produce a silvery mirror when aldehydes are present. When Benedict's reagent is used, the aldehyde group of an aldose is readily oxidized, indicated by a red precipitate of Cu2O. Note: to test specifically for glucose, one may utilize the enzyme glucose oxidase which does not react with other reducing sugars.
What are the mechanics of transcription?
Transcription produces a copy of only one of the two strands of DNA. During initiation of transcription, several enzymes, including helicase and topoisomerase, are involved in unwinding the double-stranded DNA and preventing formations of supercoils. The transcription results in a single strand of mRNA, synthesized from one of the two nucleotide strands of DNA called the template strand (or antisense strand). The newly synthesized mRNA strand is both antiparallel and complementary to the DNA template strand.
Describe the end of transcription
Transcription will continue along the DNA coding region until the RNA polymerase reaches a termination sequence or stop signal, which results in the termination of transcription. The DNA double helix then reforms and the primary transcript formed is termed heterogeneous nuclear RNA (hnRNA), mRNA is derived from hnRNA vis posttranscriptional modifications.
Describe transduction
Transduction is the only bacterial genetic recombination process that requires a vector ( a virus that carries genetic material from one bacterium to another). Viruses are obligate intracellular pathogens, which means they cannot reproduce outside of a host cell. Because of this, bacteriophages (viruses that infect bacteria) can accidentally incorporate a segment of host DNA during assembly, this may be passed into the new host cell giving the new host additional genes.
Describe tRNA
Transfer RNA is responsible for converting the language of nucleic acids to the language of amino acids and peptides. Each tRNA molecule contains a folded strand of RNA that includes a three-nucleotide anticodon. This anticodon recognizes and pairs with the appropriate codon on an mRNA molecule while in the ribosome. There are 20 amino acids in eukaryotic proteins, each of which is represented by at least one codon. To become part of a nascent polypeptide in the ribosome, amino acids are connected to a specific tRNA molecule -- such tRNA molecules are said to be charged or activated with an amino acid. Mature tRNA is found in the cytoplasm.H
What are the three types of bacterial genetic recombination?
Transformation, conjugation, and transduction
What is a translocation mutation?
Translocation mutations occur when a segment of DNA from one chromosome is swapped with a segment of DNA from another chromosome.
What are transposons?
Transposons are genetic elements capable of inserting and removing themselves from a genome. This has been seen in prokaryotes and eukaryotes. If a transposon is inserted within a coding region of a gene, that gene may be disrupted.
Describe the structure of triacylglycerols
Triacylglycerol, also called triglycerides, are composed of three fatty acids bonded by ester linkages to glycerol. Overall, these compounds are nonpolar and hydrophobic. This contributes to their insolubility in water, as the polar hydroxyl groups of the glycerol component and the polar carboxylates of fatty acids are bonded together, decreasing their polarity. Note: for most naturally occurring triacylglycerols, it is rare for all three fatty acids to be the same.
What are triacylglycerols?
Triacylglycerols are a class of lipids specifically used for energy storage. From the body's point of view, lipids in general are a fantastic way to store energy. This is true for two major reasons: 1. The carbon atoms of fatty acids are more reduced than those of sugars, which contain numerous alcohol groups. The result of this is that the oxidation of triacylglycerol yields twice the amount of energy per gram as carbohydrates, making this a far more energy-dense storage mechanism compared to polysaccharides like glycogen. 2. Triacylglycerols are hydrophobic. They do not draw in water and do not require hydration for stability. This helps decrease their weight, especially in comparison to hydrophilic polysaccharides.
Describe triacylglycerol synthesis
Triacylglycerols, the storage form of fatty acids, are formed by attaching three fatty acids (as fatty acyl-CoA) to glycerol. The triacylglycerol formation from fatty acids and glycerol 3-phosphate occurs primarily in the liver and somewhat in adipose tissue, with a small contribution directly from the diet, as well. In the liver, triacylglycerols are packaged and sent to adipose tissue as very low density lipoproteins (VLDL), leaving only a small amount of stored triacylglycerols.
Describe T3 and T4
Triiodothyronine (T3) and thyroxine (T4) are both produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid. The number 3 and 4 refer to the number of iodine atoms attached to the tyrosine. Thyroid hormones are capable of resetting the basal metabolic rate of the body making energy production more or less efficient, as well as altering the utilization of glucose and fatty acids. Increased amounts of T3 and T4 will lead to increased cellular respiration. This leads to increased protein and fatty acid turnover by speeding up both synthesis and degradation of these compounds. High plasma levels of thyroid hormones will lead to decreased TSH and TRH synthesis; negative feedback prevents excessive secretion of T3 and T4.
Draw Tryptophan
Trp; W
Describe trypsin
Trypsin cleaves at the carboxyl end of arginine and lysine. It breaks apart the amine bond by adding a hydrogen atom to the amide nitrogen and an OH group to the carbonyl carbon in a process known as hydrolysis. *peptides are written from N terminus to C terminus
What are diastereomers?
Two sugars that are in the same family (both are either ketoses or aldoses, and have the same number of carbons) that are not identical and are no mirror images of each other Basically: stereoisomers that are not mirror images
What types of cells are insensitive to insulin?
Two types: nervous tissue and red blood cells. Nervous tissue derives energy from oxidating glucose to CO2 and water in both the well-fed and normal fasting states, Only in prolonged fasting does this situation change. Red blood cells can only use glucose anaerobically for all their energy needs, regardless of the individual's metabolic state.
Draw Tyrosine
Tyr; Y This is just phenylalanine with an OH attached!
Describe nucleotide excision repair
Ultraviolet light induces the formation of dimers between adjacent thymine residues in DNA. The formation of thymine dimers interferes with DNA replication and normal gene expression and distorts the shape of the double helix. Thymine dimers are eliminated from DNA by a nucleotide excision repair (NER) mechanism, which is a cut-and-patch process: First, specific proteins scan the DNA molecule and recognize the lesion because of a bulge in the strand. An excision endonuclease then makes nicks in the phosphodiester backbone of the damaged strand on both sides of the thymine dimer and removes the defective oligonucleotide. DNA polymerase can then fill in the gap by synthesizing DNA in the 5' to 3' direction, using the undamaged strand as a template. Finally, the nick in the strand is sealed by DNA ligase.
Describe uncompetitive inhibition
Uncrossed inhibition Uncompetitive inhibition binds only to the ES complex and locks the substrate in the enzyme preventing its release thus it lowers Km (increases affinity) and in turn decreases Vmax.
How do proteins differ from carbohydrates in terms of absorption?
Unlike carbohydrates, which must be broken down into monosaccharides for absorption, proteins can be broken down into di- and even tripeptides and can be absorbed across the small intestine wall.
What causes the release of aldosterone?
Unlike glucocorticoids, aldosterone is primarily under the control of the renin-angiotensin-aldosterone system. Decreased blood pressure causes the juxtaglomerular cells of the kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen, to its active form, angiotensin I. Angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs. Angiotensin II stimulates the adrenal cortex to secrete aldosterone. Once blood pressure is restored, there is a decreased drive to stimulate renin release, thus serving as the negative feedback mechanism for this system.
Describe exhalation
Unlike inhalation, exhalation does not need to be an active process. Simple relaxation of the external intercostal muscles will reverse the process of inhalation. AS the diaphragm and external intercostals relax, the chest cavity decrease in volume. This will cause pressure in the intrapleural space to go up. Now pressure in the intrapleural space is higher in the lungs, which is still at atm pressure. Thus, air will be pushed out, resulting in exhalation. During active tasks, we can speed this process up by using the internal intercostal muscles and abdominal muscles, which oppose the external intercostals and pull the rib cage down. his actively decrease the volume of the thoracic cavity.
Describe the energy source of cardiac muscle
Unlike other tissues of the body, cardiac myocytes prefer fatty acids as their major fuel, even in the well-fed state. When ketones are present during prolonged fasting, they can also be used. Thus, not surprisingly, cardiac myocytes most closely parallel skeletal muscled during extended periods of exercise. In patients with cardiac hypertrophy (thickening of the heart muscle), this situation reverses to some extent. In a failing heart, glucose oxidation increases and beta-oxidation falls.
Describe unsaturated fatty acids
Unsaturated fatty acids are regarded as "healthier" fats because they tend to have one or more double bonds and exist in liquid form at room temperature; in the plasma membrane, these characteristic s impart fluidity to the membrane. Humans can only synthesize a few of the unsaturated fatty acids the rest come from essential fatty acids in the diet that are transported as triacyclglycerols from the intestine inside chylomicrons.
What is the formula for velocity of a catalytic reaction?
V= Kcat/Km [E][S]
Describe VLDL
VLDL metabolism is similar to that of chylomicrons; however, VLDL is produced and assembled in liver cells. Like chylomicrons, the main function of LDL is the transport of triacylglycerols to other tissues. VLDLs also contain fatty acids that are synthesized from excess glucose or retrieved from chylomicron remnants.
What is the function of VLDL?
VLDL transports triacylglycerols and fatty acids from livers to tissues -- they also contain small amounts of cholesteryl esters
Draw Valine
Val; V
Describe veins
Veins are thin-walled, inelastic vessels that transport blood to the heart. Veins have much less smooth muscle than arteries. The smaller amount of smooth muscle in the walls of veins gives them less recoil than arteries. Furthermore, veins are able to stretch to accommodate larger quantities of blood. In fact, 3/4 of our total blood volume may be in venous circulation at any one time. Note: Even though the volume of arterial blood is normally much less than the volume of venous blood, the total volume passing through either side of the heart per unit time (cardiac output) is the same.
What keeps blood from pooling in our feet?
Venous valves and the squeezing of skeletal muscles in the legs
What happens as CO2 in the blood rises?
Ventilation increases so that more CO2 os exhaled, causing carbon dioxide levels in the blood to fall.
What controls ventilaton?
Ventilation is primarily regulated by a collection of neurons in the medulla oblongata called the ventilation center that fire rhythmically tp cause regular contraction of respiratory muscles. These neurons contain chemoreceptors that are primarily sensitive to CO2 concentration. Note: These cells also respond to changes in oxygen concentration, although this tends to have significance only during periods of significant hypoxemia.
What are prions?
Very small infectious proteins (non-living). They cause disease by triggering misfolding of other proteins, usually through the conversion of a protein from an alpha-helical structure to a beta-pleated sheet. This drastically reduced the solubility of the protein, as well as the ability of the cell to degrade the protein. Eventually protein aggregates form, interfering with cell function.
How is gene expression controlled in prokaryotes?
Via the usage of operons. Operons are a cluster of genes transcribed as a single mRNA. The Jacob-Monod model is used to describe the structure and function of operons. In this model, operons contain structural genes, an operator site, and a regulator gene. The structural gene codes for the protein of interest. Upstream of the structural gene is the operator site, a non-transcribable region of DNA that is capable of binding a repressor protein. Further upstream is the promoter site, which is similar in function to promoters in eukaryotes: it provides a place for RNA polymerase to bind. Furthest upstream is the regulator gene, which codes for a protein none as the repressor. There are two types of operons: inducible systems and repressible systems.
Describe the viral genome
Viral genomes can be a few genes or several hundred. They van be single- or double-stranded. They can be composed of DNA or RNA, and the single stranded RNA can be positive sense or negative sense.
Describe the progeny release phase of the virus life cycle
Viral progeny may be released in multiple ways: 1. Viral invasion may initiate cell death which results in spilling of the viral progeny 2. The host cell may lyse as a result of being filled with a very large number of virions (Note: lysis is actually a disadvantage for the virus because the virus can no longer use the cell to carry out its life cycle). 3. A virus can leave a cell by fusing with its plasma embrane, a process known as extrusion. A virus that does this leaves the host cell alive for use and is said to be in a productive cycle.
Describe viroids
Viroids are very small(sub viral) pathogens consisting of a very short circular single-stranded RNA that infects plants. Viroids can bind to a large number of RNA sequences and can silence genes in the plant genome. This prevents the synthesis of necessary proteins resulting in metabolic and structural damage to the cell. Note: Viroids are classically though of as plant pathogens but a few examples of human viroids do exist.
Describe viruses
Viruses are composed of genetic material, a protein coat, and sometimes an envelope containing phospholipids. The protein coat is known as a capsid- which may be surrounded by an envelope. Note: The envelope is very sensitive to heat, detergents, and desiccation; thus enveloped viruses are easier to kill. Those without envelopes are more likely to persist. Viruses have no organelles and no nucleus
Why aren't viruses considered living?
Viruses are not considered living things because they are acellular, cannot reproduce without a host cell, and may use RNA as their genetic material.
Describe the infection portion of a virus life cycle
Viruses infect cells by attaching to specific receptors and can then enter the cell by fusing with the plasma membrane, being brought in by endocytosis, or injecting their genome into the cell. Viruses can only infect a specific set of cells because as mentioned they must bind to specific receptors on the host cell. Once the virus and cell match and get close enough, the envelope and the plasma membrane of the cell will fuse allowing entry of the virion into the host cell. Sometimes a host cell may mistake a virus bound to the membrane as nutrients or other useful molecules and will actually bring the virus into the cytoplasm via endocytosis. Depending on the virus, different portions of the virion will be inserted into the host cells. Enveloped viruses such as HIV fuse with the membrane and enter the cell intact, where as bacteriophages only insert their genetic material, leaving their capsids outside the host cell.
Why are viruses obligate intracellular organisms?
Viruses need host cells to replicate because they lack ribosomes to carry out protein synthesis (they have no organelles). After hijacking a cell's machinery, a virus will replicate and produce progeny called virions which can be released to infect additional cells.
Describe vitamin A
Vitamin A, aka carotene, is an unsaturated hydrocarbon that is important in vision, growth, development, and immune function. The most significant metabolite of vitamin A is the aldehyde form, retinal, which is a component of the light sensing molecular system in the human eye. Retinol, the storage form of vitamin A, is also oxidized to retinoic acid, a hormone that regulates gene expression during epithelial development.
How does vitamin D promote bone growth?
Vitamin D is activated by parathyroid hormone and promotes the resorption of bone. The resorption of bone in response to vitamin D encourages the growth of new, stronger bone, thus overcompensating for the effect of resorbing bone.
Describe vitamin D
Vitamin D, also known as cholecalciferol, can be consumed or formed in a UV light-driven reaction in the skin. In the liver and kidneys, vitamin D is converted to calcitriol, the biologically active form of vitamin D. Calcitriol increases calcium and phosphate uptake in the intestines which promotes bone production. A lack of vitamin D can result in rickets, a condition seen in children and characterized by underdeveloped, curved long bones as well as impeded growth
Describe vitamin E
Vitamin E characterizes a group of closely related lipids called tocopherols and tocotrienols. These are characterized by a substituted aromatic ring with a long isoprenoid side chain and are characteristically hydrophobic. Tocopherols are biological antioxidants. The aromatic ring reacts with free radicals, destroying them. This, in turn, prevents oxidative damage, an important contributor to the development of cancer and aging.
Describe vitamin K
Vitamin K is actually a group of compounds, including phylloquinone (K1) and the menaquinones (K2). Vitamin K is vital to the posttranslational modifications required to form prothrombin, an important clotting factor in the blood. The aromatic ring of vitamin K undergoes a cycle of oxidation and reduction during the formation of prothrombin. Vitamin K is also required to introduce calcium-binding sites on several calcium-dependent proteins. Vitamin K is for Koagulation.
What is the Goldman-Hodgkin-Katz voltage equation?
Vm= 61.5 log
What is the formula for Vmax?
Vmax = [E]Kcat *Kca measures the # of substrate molecules "turned over" or converted to product per enzyme per second *Vmax is in M/s while kcat is in s^-1
Describe waxes
Waxes are esters of long-chain fatty acids with long-chain alcohols. AS one might expect, they form pliable solids at room temperature (what we generally think of as wax). This is due to the fact that wax is composed of a long-chain fatty acid and a long-chain alcohol, which contribute to the high melting point. Biologically, they function as protection for both plants and animals. In plants, waxes are secreted as a surface coating to prevent excessive evaporation and to protect against parasites. In animals, waxes are secreted to prevent dehydration, as a water-repellant to keep skin and feathers dry, and as a lubricant--waxes are EXTREMELY hydrophobic and rarely found in the cell membranes of animals; if present in the cell membrane, waxes can provide both stability and rigidity within the nonpolar tail region ONLY.
Describe how alcohol can lead to acetyl-CoA formation
When alcohol is consumed in moderate amounts, the enzymes alcohol dehydrogenase and acetaldehyde dehydrogenase convert it to acetyl-CoA. However, this reaction is accompanied by NADH build-up, which inhibits the Krebs cycle. Therefore the acetyl-CoA formed through this process is used primarily to synthesize fatty acids.
Describe termination of translation
When any of the three stop codons moves into the A site, a protein called released factor (RF) binds to the termination codon, causing a water molecule to be added to the polypeptide chain. The addition of this water molecule allows peptidyl transferase and termination factors to hydrolyze the completed polypeptide chain from the final tRNA. The polypeptide chain will then be released from the tRNA in the P site, and the two ribosomal subunits will dissociate.
When is glucagon released?
When blood glucose levels are low
How do you name fatty acids?
When describing a fatty acid, the total number of carbons is given along with the number of double bounds, written as carbons: double bonds.
When is an amino acid protonated?
When pH < pKA
When is an amino acid deprotonated?
When pH > pKA
What occurs in isolation of species?
When populations of the same species are separated for a long period of time, they get exposed to different evolutionary pressures that lead to different adaptive changes. If enough time passed the changes would be so sufficient that the progeny of these populations would no longer freely interbreed. The populations would become separate species.
What is paracrine signaling?
When signals act on cells in the local area
What is autocrine signaling?
When signals act on the same cell that secreted the signal
What is the job of the epiglottis?
When swallowing it covers the trachea (tube that leads to the lung) which ensures that food and liquid will go down the esophagus towards the stomach and not into the lungs
How does clot formation occur?
When the endothelial lining of a blood vessel is damaged, the collagen and tissue factor underlying the endothelial cells are exposed. This results in a cascade of events known as the coagulation cascade, ultimately resulting in the formation of a clot over the damaged area. The endpoint of this process is when prothrombin is activated to form thrombin by thromboplastin. Thrombin can then convert fibrinogen into fibrin, Fibrin ultimately forms small fibers that aggregate and cross-link into a woven structure, like a net, that captures red blood cells and other platelets forming a stable clot over the area of damage.
What is a missense mutation?
a mutation where one amino acid substitutes for another This is like saying "I have a rat." instead of "I have a cat"
Describe lipoproteins
While free fatty acids are transported through the blood in association with albumin, a carrier protein, triacylglycerol and cholesterol are transported in the blood as lipoproteins: aggregates of apolipoproteins and lipids. Lipoproteins are named according to their density, which increases in direct proportion to the percentage of protein in the particle. Chylomicrons are the least dense with the highest fat-to-protein ratio. VLDL is slightly more dense, followed by IDL, LDL, and HDL.
Which is more reliable: genomic libraries or cDNA libraries?
While genomic libraries contain the entre genome of an organism, genes may by chance split into multiple vectors. Therefore, only cDNA libraries can be used to reliably sequence specific genes and identify disease-causing mutations, produce recombinant proteins (such as insulin, clotting factors, or vaccines), or produce transgenic animals.
What is true about populations in Hardy-Weinberg equilibrium?
While genotype frequencies may change, allele frequencies remain the same
Where does lymphocyte maturation occur?
Will take place in one of 3 locations: Lymphocytes that mature in the spleen or in lymph nodes are referred to as B-cells, and those that mature in thymus are called T-cells.
Which mutation is more severe: a point mutation or a frameshift mutation
a frameshift mutation
In high doses, aspirin functions as a mitochondrial uncoupler. How would this affect glycogen stores? a. It causes depletion of glycogen stores. b. It has no effect on glycogen stores. c. It promotes additional storage of glucose as glycogen. d. Its effect on glycogen stores varies from cell to cell.
a. It causes depletion of glycogen stores. Uncouplers inhibit ATP synthesis without affecting the electron transport chain. Because the body must burn more fuel to maintain the proton-motive force, glycogen stores will be mobilized to feed into glycolysis, then the TCA, and finally oxidative phosphorylation. (ADP builds up)
what tissues need insulin for effective glucose uptake?
adipose tissue and resting skeletal muscle
When is the poly A tail added?
after completion of transcription
What happens at Complex III of the ETC?
aka CoQH2-cytochrome c oxidoreductase or cytochrome reductase, this complex facilitates the transfer of electrons from coenzyme Q to cytochrome c in a few steps. The following steps involve the oxidation ad reduction of cytochromes: proteins with heme groups in which iron is reduced to Fe2+ and reoxidized to Fe3+: CoQH2 + 2 cytochrome c [with Fe3+] --> CoQ + 2 cytochrome c [with Fe2+] + 2H+ In the transfer of electrons from iron, only one electron is transferred per reaction, but because coenzyme Q has two electrons t transfer, two cytochrome c molecules will be needed. Complex III's main contribution to the proton motive force is via the Q cycle: In the Q cycle, two electrons are shuttled from a molecule of ubiquinol (CoQH2) near the intermembrane space to a molecule of ubiquinone (CoQ) near the mitochondrial matrix. Another two electrons are attached to heme moieties, reducing two molecules of cytochrome c. A carrier containing iron and sulfur assists this process. In shuttling these electrons, four protons are also displaced to the intermembrane space; therefore, the Q cycle continues to increase the gradient of the proton-motive force across the inner mitochondrial membrane.
What happens at Complex IV of the ETC?
aka cytochrome c oxidase This complex facilitates the culminating step of the electron transport chain transfer of electrons from cytochrome c to oxygen, the final electron acceptor. This complex includes subunits of cytochrome a cytochrome a3, and Cu2+ ions. Together, cytochromes a and a3 make up cytochrome oxidase. THrough a series of redox reactions, cytochrome oxidase gets oxidized as oxygen, become more reduced, and forms water. This s the final location on the transport chain where proton pumping occurs, as two protons are moved across the membrane.
Describe membrane associated proteins
aka peripheral proteins, membrane-associated proteins may be bound through electrostatic interactions with the lipid bilayer, especially at lipid rafts, or to other transmembrane or embedded proteins like the G proteins found in G protein-coupled receptors. These may act as recognition molecules or enzymes.
Describe the G1/S Checkpoint
aka the restriction point. Here the cell checks to make sure the DNA is in good enough condition for synthesis. If there has been damage to the DNA, the cell cycle goes into arrest until the DNA has been repaired. The main protein in control of this is p53.
A six-carbon sugar with an aldehyde group is called what? What about a five-carbon sugar with a ketone group?
aldohexose; ketopentose
What are the glucogenic amino acids?
all except leucine and lysine
What's the difference between alpha-1,4 glycogen bonds and alpha-1,6 glycogen bonds?
alpha-1,4 keeps the same branch moving "4ward"; alpha-1,6 (one-six) "puts a branch in the mix".
What digestive enzymes are found in saliva?
amylase and lipase: Salivary amylase is capable of hydrolyzing starch into smaller sugars (maltose and dextrins), while lipase catalyzes the hydrolysis of lipids. The amount of chemical digestion that takes place in the mouth is minimal though because food does not stay in the bough for long. Our muscular tongue forms the food into a bolus, which is forced back to the pharynx and swallowed.
What causes ovulation?
an LH surge
If a neuron signals to a gland or a muscles rather than another neuron, the postsynaptic cell is known as....
an effector.
ester
an organic compound made by chemically combining an alcohol and an organic acid RCOOR
Where is ACTH released from?
anterior pituitary gland
What is a holoenzyme?
apoenzyme + cofactor *an apoenzyme is when the enzyme DOES NOT have its cofactor
What is the normal range of blood pressure?
between 90/60 and 120/80
What are enzymes?
biological catalysts
Where are white blood cells produced?
bone marrow
Tracts are a...
bundle of axons. Unlike nerves, tracts only carry one type of information. *The cell bodies of neurons in the same tract are grouped into nuclei
A nerve is a...
bundle of neurons
What stimulates the gallbladder to release bile?
cholecystokinin (CCK)
Which complex of the ETC has the highest reduction potential?
complex IV (reduction potential increases along the ETC)
Constitutional isomer
compounds with the same molecular formula but different connections among their atoms
What molecules are responsible for the cell clycle?
cyclins and cyclin dependent kinases (CDK) In order to be activated, the CDKs require the presence of the right cyclins. During the cell cycle, concentrations of the various cyclins increase and decrease during specific stages. These cyclins bind to CDKs creating an active CDK complex. The complex can then phosphorylate transcription factors. The transcription factors then promote the transcription of genes required for the next stage of the cell cycle.
Describe erythropoietin
cytokine produced by the kidney which stimulates bone marrow to carry out erythropoiesis. It is secreted in response to low levels of oxygen in the blood.
Where does glycolysis take place?
cytoplasm of the cell
Where does gluconeogenesis take place?
cytosol of the liver
What is heterochromatin?
densely packed, unacetylated chromatin that is inactive
What are epimers?
diastereomers that differ at exactly one chiral carbon
Where do most of the fatty acids used for fuel come from?
diet
What is another name for the vas deferens?
ductus deferens
What are the three sections of the small intestine in order?
duodenum, jejunum, and ileum
What is bone derived from?
embryonic mesoderm
Is bond breaking endothermic or exothermic?
endothermic EXCEPT for when it comes to ATP and GTP. Due to all the negative charges in close proximity in ATP and GTP, removing the terminal phosphate actually releases energy, which powers our cells.
What hormones' are involved in the stress response?
epinephrine and cortisol Cortisol is understood to mediate long-term (slow) stress responses, while catecholamines are understood to control short-term (fast) stress responses. In fact, cortisol actually increases the synthesis of catecholamines as well, resulting in an increase in catecholamine release.
What types of cells do ovaries have?
epithelial
What is the common name for ethanol?
ethyl alcohol
Describe glyceraldehyde-3-phosphate dehydrogenase
glyceraldehyde-3-phosphate dehydrogenase catalyzes an oxidation and addition of inorganic phosphate (Pi) to its substrate, GAP. This results in the production of a high energy intermediate 1,3-bisphosphoglycerate (1,3BPG) and the reduction of NAD+ to NADH. If glycolysis is aerobic the NADH produced can be oxidized by the mitochondrial electron transport chain, providing energy for ATP synthesis by oxidative phosphorylation.
Draw Arginine
good job
Draw glycine
good job
Draw leucine
good job
Draw methionine
good job
Draw out glycolysis
good job
Draw proline
good job
What plays the largest role in the stability of tertiary structures of proteins?
hydrophobic interactions between R groups of amino acids
antidiuretic hormone (ADH)
influences the absorption of water by kidney tubules A hormone produced by the neurosecretory cells in the hypothalamus that stimulates water reabsorption from kidney tubule cells into the blood and vasoconstriction of arterioles.
What are the three stages of translation?
initiation, elongation, and termination
Endothelial tissue
inner lining of the walls of blood and lymph vessels
Where does transcription take place?
inside the nucleus
What is IRV?
inspiratory reserve volume- the volume of additional air that can be forcibly inhaled after a normal inhalation
What is the rate limiting enzyme of the citric acid cycle?
isocitrate dehydrogenase
What is the common name for 2-propanol?
isopropyl alcohol
What type of hormone is glucagon?
it is a peptide hormone; thus it is water soluble and can act rapidly but is degraded quickly
What type of hormone is insulin?
it is a peptide hormone; thus it is water soluble and can act rapidly but is degraded quickly
Describe Meiosis II
it is very similar to mitosis in that the sister chromatids. rather than homologous pairs, are separated from each other
What is the function of DNA polymerase gamma?
it replicates mitochondrial DNA
What is the rate-limiting enzyme in fermentation?
lactate dehydrogenase
What is the shape for a regular Michaelis-Menten plot?
logarithmic
Describe Cellobiose
made up of two glucose molecules joined by a beta-1,4 linkage
Where does beta oxidation occur?
mitochondria
What is the pathway of food?
mouth, esophagus, pharynx, stomach, small intestine, large intestine, rectum, anus
Describe disruptive natural selection
natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve Disruptive selection is facilitated by the existence of polymorphisms -- naturally occurring differences in form between members of the same population, such as light and dark coloration in the same species of butterfly.
What is the endomembrane system?
network of organelles and structures that function in the transport of proteins/other macromolecules in and out of the cell: Ex: golgi and ER
Is rRNA coding or noncoding?
noncoding; it is also very small
Is tRNA coding or noncoding?
noncoding; it is also very small
What are nares?
nostrils
How many alleles does a gamete have?
one allele for any given trait
What is a deleterious mutation?
one that is detrimental to an organism's health; it lowers fitness
What are chimeras?
organisms that contain cells from two different lineages
chorion
outermost layer of the fetal membrane placenta
What are catalysts sensitive to?
pH, temperature, and salinity changes *pH: enzymes are maximally active within a small pH range; outside of the ionization of this range, activity drops quickly with changes in pH as active site changes and the protein is denatured *Temperature: Enzyme catalyzed reactions tend to double in velocity for every 10 degrees celsius increase until the optimum temp is reached (in humans this is 37 degrees celsius). After this, activity falls off sharply as the enzyme will denature. --some enzymes that are overheated can regain function if cooled *Salinity: Altering the [salt] can change enzyme activity in vitro. Increasing levels of salt can disrupt hydrogen and ionic bonds, causing a partial change in the conformation of the enzyme, and in some cases causing denaturation
What part of the Hardy-Weinberg Equation represents the frequency of the dominant phenotype?
p^2 + 2pq
All of the glands of the body are innervated by the....
parasympathetic nervous system (this excludes the sweat glands which are actually innervated by the SNS)
List the following membrane components on order from most plentiful to least plentiful: carbohydrates, lipids, proteins, nucleic acids
phospholipids > proteins > carbohydrates > nucleic acids
Are silica gel and alumina polar or nonpolar?
polar
What is the archenteron?
primitive gut formed during gastrulation--it is the invagination into the blastocoel, in deuterostomes, it will later develop into the gut. In protostomes, it will later develop into the mouth. Deuterostomes -> deu -> -> deu-deu--> deuterostomes develop the anus from the blastopore
What are colligative properties?
properties that depend on the # of solute particles, but not on the type
What type of virus is HIV?
retrovirus Retroviruses are enveloped, single-stranded RNA virus, the virion contains two identical RNA molecules. These viruses carry an enzyme known as reverse transcriptase, which synthesizes DNA from single stranded RNA. The DNA integrate into the host cell genome, where it is replicated and transcribed as if it were the host cell's own DNA. Integration of the genetic material into the host cell genome allows the cell to be infected indefinitely, so the only way to remove the infection is to kill the infected cell
What is the visceral pleura?
serous membrane that covers lungs
Where is rRNA made?
the nucleolus
What is the F generation?
the offspring (filial generation)
Sugar hemiacetal Formation
the oxygen in the alcohol functions as a nucleophile, attacking the carbonyl carbon, and generating a hemiacetal. Note: when we move from Fischer projection to Haworth projection, any group on the right in the Fischer projection will point down.
What is hematocrit?
the ratio of the volume of red blood cells to the total volume of blood; it tells us how much of a blood sample consists of red blood cells and is given as a percentage
How many isoprene unites are in a sesquiterpene?
three; sesqui- means 1.5 and 1.5 terpenes means a total of 3 isporenes
How does mRNA exit the nucleus?
through nuclear pores
What is the role of surfactant?
to reduce surface tension within the fluid lining the alveoli
What is TLC?
total lung capacity- the maximum volume of air in the lungs when one inhales completely; usually around 6 to 7 liters
What is the Michaelis-Menten equation?
v = (vmax [S])/(Km + [S])
What is the formula for migration velocity in electrophoresis?
v= Ez/f *where E is the electrical field strength, z is the net charge, and f is the frictional coefficient
The _____ is surrounded by muscle that raises and lowers the testes to ____.
vans deferens maintain a constant temperature suitable for sperm production
Which blood vessels have valves?
veins
What is VC?
vital capacity- the difference between the minimum and maximum volume of air in the lungs
What is emesis?
vomiting
What is the Gibbs free energy equation?
∆G = ∆H - T∆S
What is the formula for calculating standard free energy?
∆G= ∆G° + RTlnQ where Q is the reaction quotient
What is the formula for the pressure differential across circulation?
∆P = CO x TPR
What is Mendel's first law?
♦ Mendel's First Law: The Law of Segregation. At meiosis, alleles separate (or segregate) from each other such that each gamete (egg or sperm) receives one copy from each allele pair.